Add an input driver for the keypad on STMPE I/O expanders.  This driver
uses the common support provided by the STMPE MFD driver.
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: NLinus Walleij <linus.walleij@stericsson.com>
Signed-off-by: NRabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>