net/irda: fix error return code in bfin_sir_open()

Fix to return -ENOMEM in the irlap_open() error handling case instead
of 0(overwrite to 0 by bfin_sir_startup()), as done elsewhere in this
function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>