msm: 8226: configure GPIO multiplexing for SPI_CS on msm8226 only

GPIOs 2 is used for SPI_CS communication on msm8226 only.
Update the configuration of this GPIO so that it is conditional based
upon the machine type.

Change-Id: I71e6b49630efe4425ad0ffe9092ecb14571ca653
Signed-off-by: Ke Liu <keliu@codeaurora.org>