rtl8187: add radio led and fix warnings on suspend

Michael Buesch reports that his rtl8187 gives warnings on suspend
("queueing ieee80211 work while going to suspend" warnings), as rtl8187
can call ieee80211_queue_delayed_work after mac80211 is suspended.

This change enhances rtl8187 led code so we can avoid queuing work after
mac80211 is suspended: now we register a radio led and make additional
checks to ensure led is off/on properly as mac80211 wants.

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>