lenovo/x200: Enable wacom digitizer support for x200t

This patch is based on commit f2b3cd63
(lenovo/x60: Support digitizer on X60t and X201t)

Tested on Thinkpad X200 Tablet (7450): all pen functionallity
works (i.e. movements, presure sensitivity and buttons)

Change-Id: I9bd18642a6ea4211dc3be065456a507fc0b72561
Signed-off-by: Alex David <opdecirkel@gmail.com>
Reviewed-on: http://review.coreboot.org/10208
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>

src/drivers/lenovo/wacom.c

@@ -34,10 +34,11 @@ static const char tablet_numbers[][5] = {
 	"6363", "6364", "6365", "6366",
 	"6367", "6368", "7762", "7763",
 	"7764", "7767", "7768", "7769",
+	/* X200t. */
+	"7448", "7449", "7450", "7453",
 	/* X201t. */
 	"0053", "0831", "2985", "3093",
 	"3113", "3144", "3239", "4184",
-	"7448", "7449", "7450", "7453",
 	"2263", "2266",
 };