- Use the consistenly PHY-specific reset routine PHY_RESET() rather than
  generic mii_phy_reset().
- Return the result of mii_mediachg() rather than blindly returning 0.
- on smsc(4), driver lock should be held to get current
  mii_media_active/mii_media_status value.

Reviewed by:	yongari
If chan is NULL, don't derefrence it.

The bluetooth setup code actually does a channel lookup during setup,
even though we haven't yet programmed in a channel. Sigh.

Tested:

* WB225 (AR9485) + bluetooth
Add bluetooth setup method functions to the HAL.