gfs2: Mark withdraws as unlikely

gfs2: Mark withdraws as unlikely

Mark the gfs2_withdrawn(), gfs2_withdrawing(), and
gfs2_withdraw_in_prog() inline functions as likely to return %false.
This allows to get rid of likely() and unlikely() annotations at the
call sites of those functions.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>