* convert phy_getinfo() to take a "gmode" flag, rather than the siba
TGSHIGH flags and then check for 2GHz. This should ensure that
gmode is set correctly even on DUALPHY NICs.
* move the siba_powerup() call and the TGSHIGH decoding into a
call to bwn_is_bus_siba(), and return an error if it's called
on anything else. We don't yet do anything else, but when we do..
Tested:
* BCM4322, 11a STA