[PATCH] ipw2100: Fix setting txpower failed problem

The ipw2100 driver misunderstood the parameter of txpower.
Tx Power off means turn off the radio, but the driver interpret it as
"can't set txpower". So when getting the txpower, it sets disabled=1 to
the iwconifg tool in managed mode. And the tool will display "Tx Power off"
when disabled=1.

Now, in managed mode, iwconfig will not show "TX Power" if the radio is not
switched off. It will only display "Tx Power off" only if the radio is killed.

Signed-off-by: Hong Liu <hong.liu@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>