commit 5ad11b50 upstream.

We can't update the Tx power on the device unless it is
running.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=101521.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>