wifi: rtl8xxxu: Put the macid in txdesc

Add a parameter macid to fill_txdesc(), implement setting it for the
gen2 version.
This is used to tell the HW who the recipient of the packet is, so that
the appropriate data rate can be selected.

Signed-off-by: Martin Kaistra <martin.kaistra@linutronix.de>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230428150833.218605-12-martin.kaistra@linutronix.de