Otherwise we'll get compile errors like:

arch/arm/plat-omap/include/mach/keypad.h:38:1: warning: "KEY" redefined
arch/arm/plat-omap/include/mach/keypad.h:39:1: warning: "PERSISTENT_KEY" redefined
...
Signed-off-by: NTony Lindgren <tony@atomide.com>