xfs: clean up state variable usage in xfs_attr_node_remove_attr

The state variable is now a local variable pointing to a heap
allocation, so we don't need to zero-initialize it, nor do we need the
conditional to decide if we should free it.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>