wifi: rtl8xxxu: fixing transmisison failure for rtl8192eu

Fixing transmission failure which results in
"authentication with ... timed out". This can be
fixed by disable the REG_TXPAUSE.

Signed-off-by: Jun ASAKA <JunASAKA@zzy040330.moe>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221217030659.12577-1-JunASAKA@zzy040330.moe