mfd: Make TPS6105X select REGMAP_I2C

This is required since
commit 7e5071199355 ("mfd: tps6105x: Use i2c regmap to access registers").

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 2db1337..4d92df6 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1071,6 +1071,7 @@
 config TPS6105X
 	tristate "TI TPS61050/61052 Boost Converters"
 	depends on I2C
+	select REGMAP_I2C
 	select REGULATOR
 	select MFD_CORE
 	select REGULATOR_FIXED_VOLTAGE