iio: resolver: ad2s1210 add missing select REGMAP in Kconfig

This driver makes use of regmap, but does not select the required
module.
Add the missing 'select REGMAP'.

Fixes: b3689e1 ("staging: iio: resolver: ad2s1210: use regmap for config registers")
Signed-off-by: Javier Carrasco <[email protected]>
Reviewed-by: David Lechner <[email protected]>
Link: https://patch.msgid.link/[email protected]
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

Author: javiercarrascocruz

drivers/iio/resolver/Kconfig

@@ -31,6 +31,7 @@ config AD2S1210
 	depends on SPI
 	depends on COMMON_CLK
 	depends on GPIOLIB || COMPILE_TEST
+	select REGMAP
 	help
 	  Say yes here to build support for Analog Devices spi resolver
 	  to digital converters, ad2s1210, provides direct access via sysfs.