toshiba_acpi: Convert to use acpi_driver

Changes toshiba_acpi to register an acpi driver and eliminates the
platform device it was using. Also eliminates most global
variables, moving them into toshiba_acpi_dev, along with some
other miscellaneous fixes and cleanup.
Signed-off-by: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>