ACPI / OSI: Add OEM _OSI string to enable dGPU direct output

For HP Inc. mobile workstation with hybrid graphics support, dGPU can
directly output to external monitors; however, Nvidia and AMD's Linux
drivers aren't able to support this feature.

The OEM _OSI string "Linux-HPI-Hybrid-Graphics" is used by BIOS to
implement dGPU direct output to external monitors.

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>

drivers/acpi/osi.c

@@ -74,6 +74,13 @@ osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = {
 	 * a BIOS workaround.
 	 */
 	{"Linux-Lenovo-NV-HDMI-Audio", true},
+	/*
+	 * Linux-HPI-Hybrid-Graphics is used by BIOS to enable dGPU to
+	 * output video directly to external monitors on HP Inc. mobile
+	 * workstations as Nvidia and AMD VGA drivers provide limited
+	 * hybrid graphics supports.
+	 */
+	{"Linux-HPI-Hybrid-Graphics", true},
 };
 
 static u32 acpi_osi_handler(acpi_string interface, u32 supported)