orinoco: Invoke firmware download in main driver

Firmware download is enabled for Agere in orinoco_cs. Symbol firmware
download has been moved out of spectrum_cs into orinoco_cs. Firmware
download is not enabled for Intersil.

Symbol based firmware is restricted to only download on spectrum_cs
based cards.

The firmware names are hardcoded for each firmware type.

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