bnx2x: mask CPL_OF interrupt

Unmasked interrupt caused "FATAL HW block attention set2 0x20" messages
to erroneously appear, as the associated interrupt is fully recoverable.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>