Revert "MIPS: Fix PAGE_MASK definition"

This reverts commit 22b14523.

It was originally sent in an earlier revision of the pfn_t patchset.
Besides being broken, the warning is also fixed by PFN_FLAGS_MASK
casting the PAGE_MASK to an unsigned long.
Reported-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: linux-kernel@vger.kernel.org
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12182/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/page.h

@@ -33,7 +33,7 @@
 #define PAGE_SHIFT	16
 #endif
 #define PAGE_SIZE	(_AC(1,UL) << PAGE_SHIFT)
-#define PAGE_MASK	(~(PAGE_SIZE - 1))
+#define PAGE_MASK	(~((1 << PAGE_SHIFT) - 1))
 
 /*
  * This is used for calculating the real page sizes