mfd: Introduce lpc_sch for Intel SCH LPC bridge

Intel Poulsbo (SCH) chipset LPC bridge controller contains several
functions. Creating and MFD driver for the LPC bridge controller allows
simultaneous use of SMBus and GPIO interfaces on the SCH.

Signed-off-by: Denis Turischev <denis@compulab.co.il>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>