Patch "495c10cc CHROMIUM: dma-buf: restore args..."
adds a workaround for a bug in mmap_region.

As the comment states ->mmap() callback can change
vma->vm_file and so we might call fput() on the wrong file.

Revert the workaround and proper fix this in mmap_region.

v2: drop the extra if in dma_buf_mmap as well
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NJason Gunthorpe <jgg@nvidia.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Link: https://patchwork.freedesktop.org/patch/399359/