bnx2x: Add support for Multi-Function UNDI

This adds the ability for bnx2x to load after UNDI is used in the
preboot environment on a multi-function interface which is not the first
interface of a given device.
Notice a side-effect is that the order by which the functions are probed and
thus interfaces appear might change, as this patch utilizes the EPROBE_DEFER
return value (and mechanism).

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>