ice: Don't allow VLAN stripping change when pvid set

Currently, if the PVID is set in the VLAN handling section of the VSI
context the driver still allows VLAN stripping to be enabled/disabled.
VLAN stripping should only be modifiable when the PVID is not set. Fix
this by preventing VLAN stripping modification when PVID is set.

Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>