rfkill: use variable instead of duplicating the expression

RFKILL_BLOCK_SW value have just been saved to prev, no need to check it
again in the if expression. This makes code a little bit easier to read.
Signed-off-by: João Paulo Rechi Vita <jprvita@endlessm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/rfkill/core.c

@@ -287,7 +287,7 @@ static void rfkill_set_block(struct rfkill *rfkill, bool blocked)
 	spin_lock_irqsave(&rfkill->lock, flags);
 	prev = rfkill->state & RFKILL_BLOCK_SW;
 
-	if (rfkill->state & RFKILL_BLOCK_SW)
+	if (prev)
 		rfkill->state |= RFKILL_BLOCK_SW_PREV;
 	else
 		rfkill->state &= ~RFKILL_BLOCK_SW_PREV;