power_supply: Add TI BQ24257 charger driver

Based on the datasheet found here:
http://www.ti.com/lit/ds/symlink/bq24257.pdf

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 4091fb0..20352a7 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -388,6 +388,13 @@
 	help
 	  Say Y to enable support for the TI BQ24190 battery charger.
 
+config CHARGER_BQ24257
+	tristate "TI BQ24257 battery charger driver"
+	depends on I2C && GPIOLIB
+	depends on REGMAP_I2C
+	help
+	  Say Y to enable support for the TI BQ24257 battery charger.
+
 config CHARGER_BQ24735
 	tristate "TI BQ24735 battery charger support"
 	depends on I2C && GPIOLIB