[POWERPC] Remove extra return statement

Found 2 instances of return one right after each other in
arch_add_memory().  This removes the superfluous one.
Signed-off-by: NManish Ahuja <mahuja@us.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/mm/mem.c

@@ -128,8 +128,6 @@ int __devinit arch_add_memory(int nid, u64 start, u64 size)
 	zone = pgdata->node_zones;
 
 	return __add_pages(zone, start_pfn, nr_pages);
-
-	return 0;
 }
 
 /*