toshiba_acpi: Add Qosmio X75-A to the alt keymap dmi list

The Toshiba Qosmio X75-A series models also come with
the new keymap layout.

This patch adds this model to the alt_keymap_dmi list,
along with an extra key found on these models.

Signed-off-by: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>