[POWERPC] Include pagemap.h in asm/powerpc/tlb.h

Fixes this powerpc build error in 2.6.22-rc6-mm1 for powerpc 64 with
CONFIG_SWAP=n :

In file included from include2/asm/tlb.h:60,
                 from /home/compudj/git/linux-2.6-lttng/arch/powerpc/mm/init_64.
c:56:
/home/compudj/git/linux-2.6-lttng/include/asm-generic/tlb.h: In function 'tlb_flush_mmu':
/home/compudj/git/linux-2.6-lttng/include/asm-generic/tlb.h:76: error: implicit declaration of function 'release_pages'
/home/compudj/git/linux-2.6-lttng/include/asm-generic/tlb.h: In function 'tlb_remove_page':
/home/compudj/git/linux-2.6-lttng/include/asm-generic/tlb.h:105: error: implicit declaration of function 'page_cache_release'
make[2]: *** [arch/powerpc/mm/init_64.o] Error 1

release_pages is declared in linux/pagemap.h, but cannot be included in
linux/swap.h because of a sparc related comment:

/* only sparc can not include linux/pagemap.h in this file
 * so leave page_cache_release and release_pages undeclared... */
#define free_page_and_swap_cache(page) \
        page_cache_release(page)
#define free_pages_and_swap_cache(pages, nr) \
        release_pages((pages), (nr), 0);

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/tlb.h

@@ -23,6 +23,8 @@
 #include <asm/mmu.h>
 #endif
 
+#include <linux/pagemap.h>
+
 struct mmu_gather;
 
 #define tlb_start_vma(tlb, vma)	do { } while (0)