block: make blk_softirq_init() static

Sparse asked whether these could be static.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-softirq.c

@@ -161,7 +161,7 @@ void blk_complete_request(struct request *req)
 }
 EXPORT_SYMBOL(blk_complete_request);
 
-__init int blk_softirq_init(void)
+static __init int blk_softirq_init(void)
 {
 	int i;