orinoco: Don't use boolean parameter to record encoding type

For WPA support we need to encode NONE, WEP and TKIP in the encoding
parameter. In anticipation of this we need to change the usage away from
the current boolean usage.

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