block/bfq_wf2q: correct weight to ioprio

The return value is ioprio * BFQ_WEIGHT_CONVERSION_COEFF or 0.
What we want is ioprio or 0.
Correct this by changing the calculation.
Signed-off-by: Yahu Gao <gaoyahu19@gmail.com>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Link: https://lore.kernel.org/r/20220107065859.25689-1-gaoyahu19@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/bfq-wf2q.c

@@ -519,7 +519,7 @@ unsigned short bfq_ioprio_to_weight(int ioprio)
 static unsigned short bfq_weight_to_ioprio(int weight)
 {
 	return max_t(int, 0,
-		     IOPRIO_NR_LEVELS * BFQ_WEIGHT_CONVERSION_COEFF - weight);
+		     IOPRIO_NR_LEVELS - weight / BFQ_WEIGHT_CONVERSION_COEFF);
 }
 
 static void bfq_get_entity(struct bfq_entity *entity)