cnic: Fix L2CTX_STATUSB_NUM offset in context memory.

The BNX2_L2CTX_STATUSB_NUM definition needs to be changed to match
the recent firmware update:

commit 078b0735
bnx2: Update firmware to 5.0.0.j3.

Without the fix, bnx2 can crash intermittently in bnx2_rx_int() when
iSCSI is enabled.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>