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>