GFS2: local functions should be static

Quiets the sparse noise:

warning: symbol 'gfs2_initxattrs' was not declared. Should it be static?

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>