bnx2x, cnic: Fix SPQ return credit

Return proper L2 and L5 SPQ (slow path queue) credits.  Previously, all
SPQ events were counted as L5 types.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>