Revert "GFS2: Re-add a call to log_flush_wait when flushing the journal"

This reverts commit 428fd95d.
Patch 428fd95d85b2 added a call to log_flush_wait to function
gfs2_log_flush. Then gfs2_log_flush calls log_write_header which submits
a write request with the REQ_PREFLUSH flag which also forces it to wait.
This patch removes the unnecessary call to log_flush_wait.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/log.c

@@ -1004,7 +1004,6 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
 		goto out_withdraw;
 
 	if (sdp->sd_log_head != sdp->sd_log_flush_head) {
-		log_flush_wait(sdp);
 		log_write_header(sdp, flags);
 	} else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle){
 		atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */