Add network QoS support for PCP to iscsi target.

[rscheff]

Summary

The Ethernet PCP codepoint should be configurable
for L2 local traffic, to allow lower latency for
iSCSI block IO. This Diff addresses the target
side only.

Test Plan

Once a PCP is configured to a portal group, validate
with tcpdump, that a 802.1Q header is injected
containing the appropriate PCP value.

[bcr]

Minor line break needed in the man page.

usr.sbin/ctld/ctl.conf.5

262 ↗

(On Diff #78104)

Line break needed here after the sentence stop.

[rscheff]

• sync man page entry

[rscheff]

• lint man

[bcr]

usr.sbin/ctld/ctl.conf.5

262 ↗

(On Diff #78107)

I meant this position here for the line break. ;-)

[bcr]

OK from manpages.