powerpc/32: Include setup.h header file to fix warnings

Make sure to include setup.h to provide the following prototypes:

  - irqstack_early_init
  - setup_power_save
  - initialize_cache_info

Fix the following warnings (treated as error in W=1):

  arch/powerpc/kernel/setup_32.c:198:13: error: no previous prototype for ‘irqstack_early_init’
  arch/powerpc/kernel/setup_32.c:238:13: error: no previous prototype for ‘setup_power_save’
  arch/powerpc/kernel/setup_32.c:253:13: error: no previous prototype for ‘initialize_cache_info’
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/setup_32.c

@@ -43,6 +43,8 @@
 #include <asm/kdump.h>
 #include <asm/feature-fixups.h>
 
+#include "setup.h"
+
 #define DBG(fmt...)
 
 extern void bootx_init(unsigned long r4, unsigned long phys);