flash: add new stm32l HD variant

Updated as per latest RM0038 Rev 6.

Change-Id: Ia11309a1cdc3b8986f808b33a5c565bdc0ba58b0
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1003
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>

src/flash/nor/stm32lx.c

@@ -646,6 +646,10 @@ static int stm32lx_get_info(struct flash_bank *bank, char *buf, int buf_size)
 				snprintf(buf, buf_size, "Z");
 				break;
 
+			case 0x1018:
+				snprintf(buf, buf_size, "Y");
+				break;
+
 			default:
 				snprintf(buf, buf_size, "unknown");
 				break;