stlink: stlink_interface_init_target use hex prefix

Change-Id: I782da74687bcf111c1f04c53b2c1120d6a034441
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/791


Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

src/jtag/stlink/stlink_interface.c

@@ -75,8 +75,7 @@ int stlink_interface_init_target(struct target *t)
 	}
 
 	if (found == 0) {
-		LOG_ERROR
-		    ("stlink_interface_init_target: target not found: idcode: %x ",
+		LOG_ERROR("stlink_interface_init_target: target not found: idcode: 0x%08x",
 				t->tap->idcode);
 		return ERROR_FAIL;
 	}