[PATCH] iio: adc: da9150-gpadc: fix build on mips CONFIG_MIKROTIK_RB532=y

[Jackie Liu <liu.yun@linux.dev>]

From: Jackie Liu <liuyun01@kylinos.cn>

kernel robot report build fail by randconfig:

[...]
drivers/iio/adc/da9150-gpadc.c:254:13: error: ‘DA9150_GPADC_CHAN_0x08’ undeclared here (not in a function); did you mean ‘DA9150_GPADC_CHAN_TBAT’?
  254 |  .channel = DA9150_GPADC_CHAN_##_id,   \
      |             ^~~~~~~~~~~~~~~~~~
drivers/iio/adc/da9150-gpadc.c:273:2: note: in expansion of macro ‘DA9150_GPADC_CHANNEL’
  273 |  DA9150_GPADC_CHANNEL(_id, _hw_id, _type,   \
      |  ^~~~~~~~~~~~~~~~~~~~
drivers/iio/adc/da9150-gpadc.c:281:2: note: in expansion of macro ‘DA9150_GPADC_CHANNEL_PROCESSED’
  281 |  DA9150_GPADC_CHANNEL_PROCESSED(GPIOD, GPIOD_6V, IIO_VOLTAGE, NULL),
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make[4]: *** [../scripts/Makefile.build:288: drivers/iio/adc/da9150-gpadc.o] Error 1
make[3]: *** [../scripts/Makefile.build:550: drivers/iio/adc] Error 2
make[3]: *** Waiting for unfinished jobs....
[...]

Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
---
 drivers/iio/adc/da9150-gpadc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iio/adc/da9150-gpadc.c b/drivers/iio/adc/da9150-gpadc.c
index 8f0d3fb63b67..ed32061aee51 100644
--- a/drivers/iio/adc/da9150-gpadc.c
+++ b/drivers/iio/adc/da9150-gpadc.c
@@ -273,6 +273,12 @@ static const struct iio_info da9150_gpadc_info = {
 	DA9150_GPADC_CHANNEL(_id, _hw_id, _type,			\
 			     BIT(IIO_CHAN_INFO_PROCESSED), _ext_name)
 
+/*
+ * Workaround for arch/mips/include/asm/mach-rc32434/rb.h
+ *   #define GPIOD 0x08
+ */
+#undef GPIOD
+
 /* Supported channels */
 static const struct iio_chan_spec da9150_gpadc_channels[] = {
 	DA9150_GPADC_CHANNEL_PROCESSED(GPIOA, GPIOA_6V, IIO_VOLTAGE, NULL),
-- 
2.25.1