To get more coverage, enable COMPILE_TEST for this driver.

While at it, to fix build on other archs, select MMP_SRAM only for ARCH_MMP
and also fix the platform header
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>