GFS2: Initialize hex string to '0'

When generating the DLM lock name, a value of 0 would skip
the loop and leave the string unchanged.  This left locks with
a value of 0 unlabeled.  Initializing the string to '0' fixes this.
Signed-off-by: Nathan Straz <nstraz@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/lock_dlm.c

@@ -241,6 +241,7 @@ static u32 make_flags(struct gfs2_glock *gl, const unsigned int gfs_flags,
 
 static void gfs2_reverse_hex(char *c, u64 value)
 {
+	*c = '0';
 	while (value) {
 		*c-- = hex_asc[value & 0x0f];
 		value >>= 4;