spi: spi-geni-qcom: Fix the interpretation of cs_change flag

Interpret and implement the cs_change flag control parameter.

If the cs_change flag is set then toggle the CS line in-between transfers
and de-assert the CS line at the end of the message.
If the cs_change flag is not set then keep the CS line asserted in-between
transfers and de-assert the CS line at the end of the message.

Change-Id: I876f1d40aec0c0f23ff303385fd8b8f551e35253
Signed-off-by: Dilip Kota <dkota@codeaurora.org>