firmware class: export nowait to userspace

When we use request_firmware_nowait(), userspace may
not want to answer negatively right away when for
example it is answering from an initrd only, but
with request_firmware() it has to in order to not
delay the kernel boot until the request times out.

This allows userspace to differentiate between the
two in order to be able to reply negatively to async
requests only when all filesystems have been mounted
and have been checked for the requested firmware file.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>