i40e/i40evf: Add support for writeback on ITR feature for X722

i40e/i40evf: Add support for writeback on ITR feature for X722

Orabug: 21764569

X722 fixes an issue from X710 where TX descriptor WB would not happen if
the interrupts were disabled. In order for the write backs to happen a
bit needs to be set in the dynamic interrupt control register called
WB_ON_ITR. With this feature, the SW driver need not arm SW interrupts to
work around the issue in X710.

Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from commit 8e0764b4d6be42459b6f517e199b8c7df43cc15c)
Signed-off-by: Brian Maly <brian.maly@oracle.com>