be2net: Issue COMMON_RESET_FUNCTION cmd during driver unload

As per SLI guideline, drivers need to issue COMMON_RESET_FUNCTION SLI
cmd during driver unload to clean up any non-persistent state
information.
Issue this cmd only if VFs are not assigned to VMs as it is possible
for PF driver to unload while it\'s VF remains functional and assigned
to a VM.

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>