ixgbe: Support 4 queue RSS on VFs with 1 or 2 queue RSS on PF

ixgbe: Support 4 queue RSS on VFs with 1 or 2 queue RSS on PF

Instead of limiting the VFs if we don't use 4 queues for RSS in the PF we
can instead just limit the RSS queues used to a power of 2.  By doing this
we can support use cases where VFs are using more queues than the PF is
currently using and can support RSS if so desired.

The only limitation on this is that we cannot support 3 queues of RSS in
the PF or VF.  In either of these cases we should fall back to 2 queues in
order to be able to use the power of 2 masking provided by the psrtype
register.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>