bnx2x: Fix AER semaphore release

Commit 7fa6f34 "AER revised" erroneously inserted an error-flow
in which a semaphore is released even though the attempt to take it
has failed.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>