x86: mm/init_XX.c declare functions before they get used

included <asm/smp.h> in mm/init_32.c for zap_low_mappings()

declared free_initmem() in asm-x86/page_XX.h

Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index d37f293..4974e97 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -47,6 +47,7 @@
 #include <asm/paravirt.h>
 #include <asm/setup.h>
 #include <asm/cacheflush.h>
+#include <asm/smp.h>
 
 unsigned int __VMALLOC_RESERVE = 128 << 20;