[PATCH v2] pwm: fix pwm-rz-mtu3.c build errors

[Randy Dunlap <rd.dunlab@gmail.com>]

From: Randy Dunlap <rd.dunlab@gmail.com>

When (MFD) RZ_MTU3=m and PWM_RZ_MTU3=y, there are numerous build errors:

ld: vmlinux.o: in function `rz_mtu3_pwm_config':
drivers/pwm/pwm-rz-mtu3.c:374: undefined reference to `rz_mtu3_disable'
ld: drivers/pwm/pwm-rz-mtu3.c:377: undefined reference to `rz_mtu3_8bit_ch_write'
ld: vmlinux.o: in function `rz_mtu3_pwm_write_tgr_registers':
drivers/pwm/pwm-rz-mtu3.c:110: undefined reference to `rz_mtu3_16bit_ch_write'
ld: vmlinux.o: in function `rz_mtu3_pwm_config':
drivers/pwm/pwm-rz-mtu3.c:382: undefined reference to `rz_mtu3_8bit_ch_write'
ld: vmlinux.o: in function `rz_mtu3_pwm_write_tgr_registers':
drivers/pwm/pwm-rz-mtu3.c:110: undefined reference to `rz_mtu3_16bit_ch_write'
ld: drivers/pwm/pwm-rz-mtu3.c:111: undefined reference to `rz_mtu3_16bit_ch_write'
ld: vmlinux.o: in function `rz_mtu3_pwm_config':
drivers/pwm/pwm-rz-mtu3.c:397: undefined reference to `rz_mtu3_enable'
ld: vmlinux.o: in function `rz_mtu3_pwm_disable':
drivers/pwm/pwm-rz-mtu3.c:259: undefined reference to `rz_mtu3_8bit_ch_write'
ld: drivers/pwm/pwm-rz-mtu3.c:264: undefined reference to `rz_mtu3_disable'
ld: vmlinux.o: in function `rz_mtu3_pwm_enable':
drivers/pwm/pwm-rz-mtu3.c:230: undefined reference to `rz_mtu3_8bit_ch_write'
ld: drivers/pwm/pwm-rz-mtu3.c:234: undefined reference to `rz_mtu3_8bit_ch_write'
ld: drivers/pwm/pwm-rz-mtu3.c:238: undefined reference to `rz_mtu3_enable'
ld: vmlinux.o: in function `rz_mtu3_pwm_is_ch_enabled':
drivers/pwm/pwm-rz-mtu3.c:155: undefined reference to `rz_mtu3_is_enabled'
ld: drivers/pwm/pwm-rz-mtu3.c:162: undefined reference to `rz_mtu3_8bit_ch_read'
ld: vmlinux.o: in function `rz_mtu3_pwm_read_tgr_registers':
drivers/pwm/pwm-rz-mtu3.c:102: undefined reference to `rz_mtu3_16bit_ch_read'
ld: drivers/pwm/pwm-rz-mtu3.c:102: undefined reference to `rz_mtu3_16bit_ch_read'
ld: drivers/pwm/pwm-rz-mtu3.c:103: undefined reference to `rz_mtu3_16bit_ch_read'
ld: vmlinux.o: in function `rz_mtu3_pwm_get_state':
drivers/pwm/pwm-rz-mtu3.c:296: undefined reference to `rz_mtu3_8bit_ch_read'

Modify the dependencies of PWM_RZ_MTU3 so that COMPILE_TEST is
still allowed but PWM_RZ_MTU3 depends on RZ_MTU3 if it is being built
but also allow the latter not to be built.

Fixes: 254d3a727421 ("pwm: Add Renesas RZ/G2L MTU3a PWM driver")
Signed-off-by: Randy Dunlap <rd.dunlab@gmail.com
Cc: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-pwm@vger.kernel.org
---
v2: fix typo in Subject;
    correct my email address while infradead.org is down;

 drivers/pwm/Kconfig |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -- a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -505,7 +505,8 @@ config PWM_ROCKCHIP
 
 config PWM_RZ_MTU3
 	tristate "Renesas RZ/G2L MTU3a PWM Timer support"
-	depends on RZ_MTU3 || COMPILE_TEST
+	depends on COMPILE_TEST
+	depends on RZ_MTU3 || RZ_MTU3=n
 	depends on HAS_IOMEM
 	help
 	  This driver exposes the MTU3a PWM Timer controller found in Renesas