(split) Remove IO_SYNC flag when writing extended file attributes on ZFS.

While it is possible to create and write file, modify its permissions, etc.
without ever doing sync, it looks odd that it is required for setting
extended file attributes on ZFS.  UFS does not do sync there too.

Samba uses those extended attributes to store some its data, and doing it
synchronously by many times reduces file creation performance for systems
without SLOG device.

Reviewed by:	delphij, jpaetzel, silence on fs@
MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
(split) Enable 8051 before downloading firmware.

Tested by:	Carlos Jacobo Puga Medina <cpm at fbsd dot es>
(split) Fix for division by zero.

MFC after:	3 days
(split) Remove unused defines.
Fix some device_printf's that were missing '\n' at the end or had
speling errors.

PR:		145319
Submitted by:	rozhuk.im gmail.com
(split) Add the D-Link DWA-125 rev D1.

Tested by myself.
(split) If eapol packets are sent at the lowest rate, key negotiation will
become more reliable.

Submitted by:	Akinori Furukoshi <moonlightakkiy at yahoo dot ca>
(split) Fix typo: s/mac_rev/mac_ver/

Submitted by:	Stefan Sperling <stsp at openbsd dot org>
(split) Drop frames that have larger than MCLBYTES.
(split) Mechanically convert to if_inc_counter().
(split) Add new USB ID.

PR:		194091
MFC after:	3 days
(split) Merge branch 'CURRENT' (commit '805bdee0')
(split) Merge branch CURRENT (commit 'd9b5edee')

Conflicts:
	sys/dev/usb/wlan/if_run.c
	r270643 (commit '746eb54a') is already fixed
(split) Merge branch 'CURRENT'

Conflicts:
	sys/net80211/ieee80211_output.c