defconfig: sa2150p: remove user space SPI device driver support

All the users of SPI interface are within kernel space therefore
this driver is not required. For regular builds it is kept to
support bring-up and debugging.

Change-Id: I60d757921c08ce0463afddba0ee686f3e3a9a1f7
Signed-off-by: Rishi Gupta <rishgupt@codeaurora.org>