iio: adc: vf610: use devm_platform_ioremap_resource

Reduces boilerplate.

Suggested by coccinelle
CHECK   drivers/iio/adc/vf610_adc.c
drivers/iio/adc/vf610_adc.c:819:1-11: 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: Fugang Duan <b38611@freescale.com>