iwl4965: set tx power after rxon_assoc

iwl4965: set tx power after rxon_assoc

Setting tx power can be deferred during scan or changing channel.
If after that correct tx power settings will not be sent to device,
we can observe transmission problems and timeouts. Force to send
tx power settings also after partial rxon change, to assure device
always be configured with up-to-date settings.

Resolves:
https://bugzilla.kernel.org/show_bug.cgi?id=36492

Cc: stable@kernel.org # 2.6.39+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>