[libata] pata_it821x: fix warning

Reported by Andrew Morton:
drivers/ata/pata_it821x.c: In function 'it821x_port_start':
drivers/ata/pata_it821x.c:609: warning: 'mtype' may be used uninitialized in
this function

Pretty horrid fix, but so's a warning..
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_it821x.c

@@ -606,7 +606,7 @@ static void it821x_display_disk(int n, u8 *buf)
 {
 	unsigned char id[41];
 	int mode = 0;
-	char *mtype;
+	char *mtype = "";
 	char mbuf[8];
 	char *cbl = "(40 wire cable)";