mm/filemap.c: use vmf_error()

These codes can be replaced with new inline vmf_error().

Link: http://lkml.kernel.org/r/20180927171411.GA23331@jordon-HP-15-Notebook-PC


Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>