bnx2x: Fix bnx2x_panic_dump for VFs

bnx2x_panic_dump() prints all kind of driver information, including slowpath
information. Since VFs don't initialize slowpath information, a VF reaching
this flow will likely cause a panic in the system as it will access NULL
pointers.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>