zy1000: fix compile error with gcc 8.1.1

The fall-through comment is not taken in consideration by gcc 8.1.1
because it is inside the braces of a C-code block.

Move the comment outside the C block.

Change-Id: I22d87b2dee109fb8bcf2071ac55fdf7171ffcf4b
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4614
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

src/jtag/zy1000/zy1000.c

@@ -265,8 +265,8 @@ COMMAND_HANDLER(handle_power_command)
 			bool enable;
 			COMMAND_PARSE_ON_OFF(CMD_ARGV[0], enable);
 			setPower(enable);
-			/* fall through */
 		}
+			/* fall through */
 		case 0:
 			LOG_INFO("Target power %s", savePower ? "on" : "off");
 			break;