orinoco: correct timeout logic in __orinoco_hw_set_tkip_key()

If the value read from HERMES_RID_TXQUEUEEMPTY becomes 0 after exactly
100 readings, we wrongly consider it a timeout.  Rewrite the clever
while loop as a for loop that does the right thing and looks simpler.

Reported by Juha Leppanen <juha_motorsportcom@luukku.com>

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>