the attached patch will add support to handle these iw_handle 
SIOC[S/G]IWRATE, SIOC[S/G]IWTXPOW and SIOC[S/G]IWPOWER.  It also  added 
some changes in ieee80211_ioctl_giwrange function to report supported 
channels and rates.  a call to ieee80211_hw_config is needed to infor 
the low level driver about these changes, I guess we might need to add 
flag to indicate which parameters was changed so the low level driver 
does not need to make extra calls.