[PPC] Add linux/pagemap.h to arch/ppc/mm/tlb.c

When compiled without swap support, arch/mm/tlb.c complains about missing
function declarations. This patch fixes the warnings.
Signed-off-by: Laurent Pinchart <laurent.pinchart@technotrade.biz>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/ppc/mm/tlb.c

@@ -27,6 +27,7 @@
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
+#include <linux/pagemap.h>
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>