mm/filemap: Allow filemap_fault Movable allocations from CMA region

There are a lot of filemap_fault Movable allocations.

      [<ffffff9b813e86f0>] get_page_from_freelist+0xa60
      [<ffffff9b813e6c90>] __alloc_pages_nodemask+0x174
      [<ffffff9b813f06f0>] __do_page_cache_readahead+0xc0
      [<ffffff9b813df73c>] filemap_fault+0x41c
      [<ffffff9b81503974>] ext4_filemap_fault+0x34
      [<ffffff9b8141fabc>] __do_fault+0x28
      [<ffffff9b8141e4a0>] handle_pte_fault+0x9d4
      [<ffffff9b8141ea14>] handle_mm_fault+0x1d0
      [<ffffff9b8129f740>] do_page_fault+0x2a0
      [<ffffff9b8129f484>] do_translation_fault+0x50
      [<ffffff9b8128135c>] do_mem_abort+0x5c
      [<ffffff9b81283478>] el0_da+0x20

The filesystem code doesn't appear to pin these pages, so allow them to be
satisfied from the CMA region in order to better utilize CMA memory.

Change-Id: I1ca6c6cc31107b9ba5e314c0be341299cf659feb
Signed-off-by: Liam Mark <lmark@codeaurora.org>