AR93xx and newer needs to stop rx before tx to avoid getting the DMA
engine or MAC into a stuck state.
This should reduce/fix the occurence of "Failed to stop Tx DMA" logspam.
Cc: stable@vger.kernel.org Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>