[S390] tlb: fix build error caused by THP

Fix this build error with !CONFIG_SWAP caused by tranparent huge pages support:

In file included from mm/pgtable-generic.c:9:0:
/linux-2.6/arch/s390/include/asm/tlb.h: In function 'tlb_remove_page':
/linux-2.6/arch/s390/include/asm/tlb.h:92:2: error: implicit declaration of function 'page_cache_release'
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/tlb.h

@@ -22,6 +22,7 @@
  */
 
 #include <linux/mm.h>
+#include <linux/pagemap.h>
 #include <linux/swap.h>
 #include <asm/processor.h>
 #include <asm/pgalloc.h>