ANDROID: 16K: madvise_vma_pad_pages: Remove filemap_fault check

Some file systems like F2FS use a custom filemap_fault ops. Remove this
check, as checking vm_file is sufficient.

Bug: 330117029
Bug: 327600007
Bug: 330767927
Bug: 328266487
Bug: 329803029
Change-Id: Id6a584d934f06650c0a95afd1823669fc77ba2c2
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>