orinoco: consolidate storage of WEP and TKIP keys

When TKIP support was added, we stored the keys separately to avoid
issues when both TKIP and WEP keys are sent to the driver.

We need to consolidate the storage to convert to cfg80211, so do this
first and try iron out the issues.

Signed-off-by: David Kilroy <kilroyd@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>