lenovo/x60: Support digitizer on X60t and X201t.

Change-Id: I5b0399a8edca3b73aa7d515d2c446c31b3239fa5
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/5239
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>