-tip: origin tree build failure

[Ingo Molnar <mingo@elte.hu>]

Today's -tip failed to build because commit 
0d204c34e85d1d63e5fdd3e3192747daf0ee7ec1 ("thinkpad-acpi: basic ALSA mixer 
support (v2)") from today's upstream kernel causes the following build failure 
on x86, for CONFIG_THINKPAD_ACPI=y && CONFIG_SOUND=m:

  drivers/built-in.o: In function `volume_alsa_notify_change':
  thinkpad_acpi.c:(.text+0x2d5c2d): undefined reference to `snd_ctl_notify'
  thinkpad_acpi.c:(.text+0x2d5c47): undefined reference to `snd_ctl_notify'

I've applied the patch below to tip:out-of-tree.

Thanks,

	Ingo

----------------->
acpi: Build CONFIG_SOUND=m build failure in CONFIG_THINKPAD_ACPI=y

Today's -tip failed to build because thinkpad_acpi.c uses sound facilities 
unconditionally, without expressing its dependency on the sound subsystem:

  drivers/built-in.o: In function `volume_alsa_notify_change':
  thinkpad_acpi.c:(.text+0x2d5c2d): undefined reference to `snd_ctl_notify'
  thinkpad_acpi.c:(.text+0x2d5c47): undefined reference to `snd_ctl_notify'

Add a Kconfig dependency on SOUND to remedy this.

Cc: Len Brown <len.brown@intel.com>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Lorne Applebaum <lorne.applebaum@gmail.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 drivers/platform/x86/Kconfig |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index f8bec62..60083e9 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -216,6 +216,7 @@ config THINKPAD_ACPI
 	depends on ACPI
 	depends on INPUT
 	depends on RFKILL || RFKILL = n
+	depends on SOUND
 	select BACKLIGHT_LCD_SUPPORT
 	select BACKLIGHT_CLASS_DEVICE
 	select HWMON