sony-laptop: check for rfkill hard block at load time

"I recently (on a flight) I found out that when I boot with the hard-switch
activated, so turning off all wireless activity on my laptop, the state
is not correctly announced in /dev/rfkill (reading it with rfkill command,
or my own gnome applet)...

After turning off and on again the hard-switch the events were right."

We can fix this by querying the firmware at load time and calling
rfkill_set_hw_state().

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Tested-by: Norbert Preining <preining@logic.at>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Mattia Dongili <malattia@linux.it>
CC: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>