SS conflicts with compile test build on i386:

    drivers/memory/ti-aemif.c:40:0: warning: "SS" redefined
    In file included from arch/x86/include/uapi/asm/ptrace.h:6:0,
                     from arch/x86/include/asm/ptrace.h:7,
                     from arch/x86/include/asm/math_emu.h:5,
                     from arch/x86/include/asm/processor.h:13,
                     from include/linux/mutex.h:19,
                     from include/linux/notifier.h:14,
                     from include/linux/clk.h:14,
                     from drivers/memory/ti-aemif.c:12:
    arch/x86/include/uapi/asm/ptrace-abi.h:23:0: note: this is the location of the previous definition
     #define SS   16

Use more descriptive name (SSTROBE) to avoid the conflict.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>