powerpc/swsusp: Include suspend.h to silence sparse warnings

Sparse emits two symbol not declared warnings for swsusp.c. The two
functions, save_processor_state() and restore_processor_state() are
declared already in suspend.h, so include it.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/swsusp.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/sched.h>
+#include <linux/suspend.h>
 #include <asm/current.h>
 #include <asm/mmu_context.h>
 #include <asm/switch_to.h>