rfkill: remove too-strict __must_check

Some drivers don't need the return value of rfkill_set_hw_state(),
so it should not be marked as __must_check.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/rfkill.h

@@ -224,7 +224,7 @@ void rfkill_destroy(struct rfkill *rfkill);
  * should be blocked) so that drivers need not keep track of the soft
  * block state -- which they might not be able to.
  */
-bool __must_check rfkill_set_hw_state(struct rfkill *rfkill, bool blocked);
+bool rfkill_set_hw_state(struct rfkill *rfkill, bool blocked);
 
 /**
  * rfkill_set_sw_state - Set the internal rfkill software block state