bnx2x: Ignore bandwidth attention in single function mode

This is a workaround for FW bug -
MFW generates bandwidth attention in single function mode, which
is only expected to be generated in multi function mode.
This undesired attention in SF mode results in incorrect HW
configuration and resulting into Tx timeout.

Signed-off-by: Shahed Shaikh <Shahed.Shaikh@cavium.com>
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>