ath5k: fix suspend-related oops on rmmod

Cumulative patch backporting the following two commits from upstream:

commit 8bdd5b9c6bd53add260756b6673a0545fbdbba21 upstream
Author: Bob Copeland <me@bobcopeland.com>

Based on a patch by Elias Oltmanns, we call ath5k_init in resume even
if we didn't previously open the device.  Besides starting up the
device unnecessarily, this also causes an oops on rmmod because
mac80211 will not invoke ath5k_stop and softirqs are left running after
the module has been unloaded.  Add a new state bit, ATH_STAT_STARTED,
to indicate that we have been started up.

commit bc1b32d6bdd2d6f3fbee9a7c01c9b099f11c579c upstream
Author: Elias Oltmanns <eo@nebensachen.de>

After a s2ram / resume cycle, resetting the key cache does not work
unless it is deferred until after the hardware has been reinitialised by
a call to ath5k_hw_reset(). This fixes a regression introduced by
"ath5k: fix suspend-related oops on rmmod".

Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Elias Oltmanns <eo@nebensachen.de>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>