driver core: firmware loader: kill FW_ACTION_NOHOTPLUG requests before suspend

This patch kills the firmware loading requests of FW_ACTION_NOHOTPLUG
before suspend to avoid blocking suspend because there is no timeout
for these requests.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>