ixgbe: Enable jumbo frames support w/ SR-IOV

This change makes it so that we can have limited support for jumbo frames
when SR-IOV is enabled.  In order to accomplish this it is necessary to
disable all VFs when the PF has jumbo frames enabled.  If the VFs then
request the same maximum frame size as the PF they will be re-enabled.  A
follow on patch will add a means of identifying when a VF can support
spanning buffers and does not need to be worried about the actual supported
max frame size.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Tested-by: Robert Garrett <robertx.e.garrett@intel.com>
Tested-by: Sibai Li <Sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>