liquidio: fix insmod failure when multiple NICs are plugged in

When multiple liquidio NICs are plugged in, the first insmod of the PF
driver succeeds.  But after an rmmod, a subsequent insmod fails.  Reason is
during rmmod, the PF driver resets the Octeon of only one of the NICs; it
neglects to reset the Octeons of the other NICs.

Fix the insmod failure by adding the missing Octeon resets at rmmod.  Keep
a per-NIC refcount that indicates the number of active PFs in a given NIC.
When the refcount goes to zero, then reset the Octeon of that NIC.

Signed-off-by: Rick Farrington <ricardo.farrington@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>