libertas: convert sleep/wake config direct commands

Confirm sleep event: they come very regularly, eventually several times per
second. Therefore we want to send the config command as fast as possible.
The old code pre-set the command in priv->lbs_ps_confirm_sleep. However, the
byte sequence to be sent to the hardware is the same for all interfaces. So
this patch make this an extern structure, initialized at module load time.

Config wake event: normal conversion to a direct command. However, I don't know
how to trigger a "HOST AWAKE" event from the firmware, so this part is
untested.

Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>