irda: Fix error propagation in ircomm_lmp_connect_response()

The variable 'ret' is set but unused, and this pointed out that
errors from irlmp_connect_response() are not propagated to the
caller.

Note that this is currently academic since irlmp_connect_response()
always returns 0. :-)

Signed-off-by: David S. Miller <davem@davemloft.net>