platform/x86: thinkpad_acpi: Adding new hotkey ID for Lenovo thinkpad

Recently we met an issue on lots of Lenovo thinkpad laptops (those
laptops are not released to market yet), the issue is that the
thinkpad_acpi.ko can't be automatically loaded as before.

Through debugging, we found the HKEY_HID is LEN0268 instead of
LEN0068 on those machines, and the MHKV is 0x200 instead of
0x100. So adding the new ID into the driver.

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>