hwmon: (ina2xx) Fix build issue by selecting REGMAP_I2C

Since a0de56c8 ("hwmon: (ina2xx) convert driver to using regmap")
the driver requires REGMAP_I2C to build.  Select it by default
in Kconfig.
Reported-by: NGuo Chunrong <B40290@freescale.com>
Cc: Marc Titinger <mtitinger@baylibre.com>
Signed-off-by: NLi Yang <leoli@freescale.com>
Fixes: a0de56c8 ("hwmon: (ina2xx) convert driver to using regmap")
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -1471,6 +1471,7 @@ config SENSORS_INA209
 config SENSORS_INA2XX
 	tristate "Texas Instruments INA219 and compatibles"
 	depends on I2C
+	select REGMAP_I2C
 	help
 	  If you say yes here you get support for INA219, INA220, INA226,
 	  INA230, and INA231 power monitor chips.