[GFS2] gfs2/ops_file.c should #include "ops_inode.h"

Every file should include the headers containing the prototypes for
its global functions (in this case for gfs2_set_inode_flags()).

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>