flash: add stm32f2x rev X

Updated as per ST RM0033 rev 5

Change-Id: I627fdab69b440b75b8e4f7c474216538fa5273a4
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1001
Tested-by: jenkins

src/flash/nor/stm32f2x.c

@@ -713,6 +713,10 @@ static int get_stm32x_info(struct flash_bank *bank, char *buf, int buf_size)
 				snprintf(buf, buf_size, "Y");
 				break;
 
+			case 0x2003:
+				snprintf(buf, buf_size, "X");
+				break;
+
 			default:
 				snprintf(buf, buf_size, "unknown");
 				break;