mfd: Add STMPE I/O Expander support

Add support for the STMPE family of I/O Expanders from
STMicroelectronics.  These devices include upto 24 gpios and a varying
selection of blocks, including PWM, keypad, and touchscreen controllers.
This patch adds the MFD core.

[l.fu@pengutronix.de: fix stmpe811 enable hook]
[l.fu@pengutronix.de: add touchscreen platform data]
Acked-by: Luotao Fu <l.fu@pengutronix.de>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index fb503e7..4410747 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -15,6 +15,7 @@
 obj-$(CONFIG_MFD_DAVINCI_VOICECODEC)	+= davinci_voicecodec.o
 obj-$(CONFIG_MFD_DM355EVM_MSP)	+= dm355evm_msp.o
 
+obj-$(CONFIG_MFD_STMPE)		+= stmpe.o
 obj-$(CONFIG_MFD_TC35892)	+= tc35892.o
 obj-$(CONFIG_MFD_T7L66XB)	+= t7l66xb.o tmio_core.o
 obj-$(CONFIG_MFD_TC6387XB)	+= tc6387xb.o tmio_core.o