ixgbe: Correct check for change in FCoE priority

ixgbe: Correct check for change in FCoE priority

Correct a check for change in FCoE priority when IEEE mode DCB is in use.
In IEEE mode a different function has to be used to get the FCoE priority
mask. Also, the check for the mask assumed that only one priority was set.
In case there should be more than one, check just the bit.

These changes help avoid link flapping issues that can come up when IEEE
DCB is in use.

(cherry picked from commit 15d447ecaff457e6f89b459e70c0770b35b35533)
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Joe Jin <joe.jin@oracle.com>