Compiling a C file which includes genalloc.h but without
spinlock_types.h being included before, we will see the compile error
below.

 include/linux/genalloc.h:54:2: error: unknown type name `spinlock_t'

Include spinlock_types.h from genalloc.h to fix the problem.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>