toshiba_acpi: Add Toshiba TECRA A50-A to the alt keymap dmi list

As bug #72551, the Toshiba TECRA A50-A series models also come with the
new keymap layout as found out by Azael Avalos, so add it to the dmi
table.

Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=76971
Reported-and-tested-by: Blindekinder <rafael.raccuia@blindekinder.com>
Cc: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>