mfd: stpmic1: Add STPMIC1 driver

STPMIC1 is a PMIC from STMicroelectronics. The STPMIC1 integrates 10
regulators, 3 power switches, a watchdog and an input for a power on key.

Signed-off-by: Pascal Paillet <p.paillet@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 12980a4..a62fb01 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -233,6 +233,7 @@
 obj-$(CONFIG_MFD_MT6397)	+= mt6397-core.o
 
 obj-$(CONFIG_MFD_ALTERA_A10SR)	+= altera-a10sr.o
+obj-$(CONFIG_MFD_STPMIC1)	+= stpmic1.o
 obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o
 
 obj-$(CONFIG_MFD_STM32_LPTIMER)	+= stm32-lptimer.o