ppc64: belong on sysconf to get current page size

Page size may change, so page size should be read through sysconf.
Suggested-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/ppc64/include/asm/page.h

@@ -18,6 +18,6 @@
 #endif
 
 #define PAGE_PFN(addr)	((addr) / PAGE_SIZE)
-#define page_size()	PAGE_SIZE
+#define page_size()	sysconf(_SC_PAGESIZE)
 
 #endif /* __CR_ASM_PAGE_H__ */