The wakeup and sleep commands need to be sent to the WILC chip only
when it is in power save mode (PSM, as controlled by "iw dev wlan0 set
power_save on/off").  The commands are relatively costly, so it pays
to skip them when possible.

iperf3 without this patch (no significant different with PSM on/off):
  TX   0.00-120.01 sec   140 MBytes  9.82 Mbits/sec
  RX   0.00-120.69 sec   283 MBytes  19.6 Mbits/sec

with this patch applied:

PSM off (TX is 46% improved, RX slightly improved; may not be significant):
  TX   0.00-120.00 sec   206 MBytes  14.4 Mbits/sec
  RX   0.00-120.48 sec   322 MBytes  22.4 Mbits/sec

PSM on (no significant change):
  TX   0.00-120.00 sec   140 MBytes  9.78 Mbits/sec
  RX   0.00-120.08 sec   257 MBytes  18.0 Mbits/sec
Signed-off-by: David Mosberger-Tang <davidm@egauge.net>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20211210203016.3680425-2-davidm@egauge.net