gfs2: Fix deadlock between gfs2_{create_inode,inode_lookup} and delete_work_func

In gfs2_create_inode and gfs2_inode_lookup, make sure to cancel any pending
delete work before taking the inode glock.  Otherwise, gfs2_cancel_delete_work
may block waiting for delete_work_func to complete, and delete_work_func may
block trying to acquire the inode glock in gfs2_inode_lookup.

Reported-by: Alexander Aring <aahringo@redhat.com>
Fixes: a0e3cc65 ("gfs2: Turn gl_delete into a delayed work")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>