ixgbe: dcb: up2tc mapping lost on disable/enable CEE DCB state

Users expect the up2tc mapping to be maintained across a DCB
enable/disable/enable transition. And since we maintain all
the other DCB attributes we should do this for up2tc mappings
as well just to be consistent. Also without this we break
user space applications that expect this to occur that
previously worked.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>