ACPI / OSI: Add OEM _OSI strings to disable NVidia RTD3

A number of Dell systems require an OEM _OSI string "Linux-Dell-Video"
as a BIOS workaround to disable RTD3 which causes systems hangs when
NVidia graphics cards are installed.  The affected Dell systems are
with system IDs: 0818, 0819, 0820, 0850, 0851, 086F, 0870, 0885 and
0886.

The form of the OEM _OSI strings is defined by each OEMs and is
discussed in Documentation/acpi/osi.txt.

Signed-off-by: Alex Hung <alex.hung@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>