fs/binfmt_elf.c: fix hugetlb memory check in vma_dump_size()

Documentation/filesystems/proc.txt says about coredump_filter bitmask,

  Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
  effected by bit 5-6.

However current code can go into the subsequent flag checks of bit 0-4
for vma(VM_HUGETLB). So this patch inserts 'return' and makes it work
as written in the document.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>	[3.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>