iio: adc: npcm: use devm_platform_ioremap_resource

Reduces local boilerplate code.
Suggested by coccinelle via coccicheck.

CHECK   drivers/iio/adc/npcm_adc.c
drivers/iio/adc/npcm_adc.c:200:1-11: WARNING: Use devm_platform_ioremap_resource for info -> regs

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: Tomer Maimon <tmaimon77@gmail.com>