ice: Add DSCP support

Implement code to handle submission of APP TLV's
containing DSCP to TC mapping.

The first such mapping received on an interface
will cause that PF to switch to L3 DSCP QoS mode,
apply the default config for that mode, and apply
the received mapping.

Only one such mapping will be allowed per DSCP value,
and when the last DSCP mapping is deleted, the PF
will switch back into L2 VLAN QoS mode, applying the
appropriate default QoS settings.

L3 DSCP QoS mode will only be allowed in SW DCBx
mode, in other words, when the FW LLDP engine is
disabled.  Commands that break this mutual exclusivity
will be blocked.

Co-developed-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>