memstick: use fully asynchronous request processing

Instead of using a separate thread to pump requests from block layer queue
to memstick, do so inline, utilizing the callback design of the memstick.

[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/memstick/core/memstick.c

@@ -249,8 +249,11 @@ EXPORT_SYMBOL(memstick_next_req);
  */
 void memstick_new_req(struct memstick_host *host)
 {
-	host->retries = cmd_retries;
-	host->request(host);
+	if (host->card) {
+		host->retries = cmd_retries;
+		INIT_COMPLETION(host->card->mrq_complete);
+		host->request(host);
+	}
 }
 EXPORT_SYMBOL(memstick_new_req);