bnx2x: fix wrong return from bnx2x_trylock_hw_lock

bnx2x_trylock_hw_lock() returns a bool :

true if succeeded to acquire the lock.
false in case of error.

-EINVAL is not an acceptable value, since its promoted to true.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>