These changes address comments by Jakub Kicinski on
commit 38b7e7f8 ("ixgbe: Do not allow LRO or MTU change with XDP").

Change the MTU check with XDP to allow any supported value and only
reject those outside of the range as opposed to rejecting any change
when XDP is active. In situations where MTU size is not supported,
return -EINVAL instead of -EPERM.

Add checks when enabling SRIOV, DCB, or adding L2FW offloaded device
as they are not supported with XDP.

CC: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Acked-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>