[POWERPC] Update lmb.h include protection to ASM_POWERPC

This file was protected by _PPC64_LMB_H, which is confusing, as the
32-bit code also uses the lmb these days.  Changed to
_ASM_POWERPC_LMB_H.
Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/lmb.h

-#ifndef _PPC64_LMB_H
-#define _PPC64_LMB_H
+#ifndef _ASM_POWERPC_LMB_H
+#define _ASM_POWERPC_LMB_H
 #ifdef __KERNEL__
 
 /*
@@ -77,4 +77,4 @@ lmb_end_pfn(struct lmb_region *type, unsigned long region_nr)
 }
 
 #endif /* __KERNEL__ */
-#endif /* _PPC64_LMB_H */
+#endif /* _ASM_POWERPC_LMB_H */