MIPS: Fix HPAGE_SIZE redefinition

MIPS: Fix HPAGE_SIZE redefinition

This patch fixes warnings like this:
  CC      fs/proc/meminfo.o
In file included from /work/linux/include/linux/mmzone.h:20,
                 from /work/linux/include/linux/gfp.h:4,
                 from /work/linux/include/linux/mm.h:8,
                 from /work/linux/fs/proc/meminfo.c:5:
/work/linux/arch/mips/include/asm/page.h:36:1: warning: "HPAGE_SIZE" redefined
In file included from /work/linux/fs/proc/meminfo.c:2:
/work/linux/include/linux/hugetlb.h:107:1: warning: this is the location of the previous definition

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>