ACPI: video: Add acpi_backlight=vendor quirk for Toshiba Portégé R100

Toshiba Portégé R100 has both acpi_video and toshiba_acpi vendor
backlight driver working. But none of them gets activated as it has
a VGA with no kernel driver (Trident CyberBlade XP4m32).

The DMI strings are very generic ("Portable PC") so add a custom
callback function to check for Trident CyberBlade XP4m32 PCI device
before enabling the vendor backlight driver (better than acpi_video
as it has more brightness steps).

Fixes: 5aa9d943 ("ACPI: video: Don't enable fallback path for creating ACPI backlight by default")
Signed-off-by: Ondrej Zary <linux@zary.sk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>