p54: Fix regression due to "net: Delete NETDEVICES_MULTIQUEUE kconfig option"

p54: Fix regression due to "net: Delete NETDEVICES_MULTIQUEUE kconfig option"

Commit e3a6d3a, entitled "net: Delete NETDEVICES_MULTIQUEUE kconfig
option" breaks p54pci and p54usb.

Additionally, the old logic always tx'ed cts frames (if enabled)
with a short preamble when [rate > 3]. (i.e. with any 802.11g rate).
Of course this isn't that bad, but it's still wrong!

(This patch also clarifies the meanings of some of the fields in the tx
header for the hardware. -- JWL)

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x]
Signed-off-by: John W. Linville <linville@tuxdriver.com>