qed: VFs to try utilizing the doorbell bar

VFs are currently not mapping their doorbell bar, instead relying
on the small doorbell window they have in their limited regview bar.

In order to increase the number of possible Tx connections [queues]
employeed by VF past 16, we need to start using the doorbell bar if
one such is exposed - VF would communicate this fact to PF which would
return the size-bar internally configured into chip, according to
which the VF would decide whether to actually utilize the doorbell
bar.

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>