iwl4965: reset firmware after rfkill off

Using rfkill switch can make firmware unstable, what cause various
Microcode errors and kernel warnings. Reseting firmware just after
rfkill off (radio on) helped with that.

Resolve:
https://bugzilla.redhat.com/show_bug.cgi?id=977053

Reported-and-tested-by: Justin Pearce <whitefox@guardianfox.net>
Cc: stable@vger.kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>