mmc: update kerneldoc

Make sure the kerneldoc comments are up to date and relevant.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 04bbe12f..63a80ea 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -99,7 +99,7 @@
 struct mmc_host;
 struct mmc_card;
 
-extern int mmc_wait_for_req(struct mmc_host *, struct mmc_request *);
+extern void mmc_wait_for_req(struct mmc_host *, struct mmc_request *);
 extern int mmc_wait_for_cmd(struct mmc_host *, struct mmc_command *, int);
 extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
 	struct mmc_command *, int);