drm/radeon: wire up a pci shutdown callback

Normally on shutdown or reboot we don't care about necessarily
making sure the hw is in a good state because the system is about
to be powered down or reset.  However, after a shutdown or reboot
in a VM, it's best to tear down the hw properly otherwise there
can be problems with the next VM use.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_device.c

@@ -639,7 +639,7 @@ void radeon_gtt_location(struct radeon_device *rdev, struct radeon_mc *mc)
  * Used at driver startup.
  * Returns true if virtual or false if not.
  */
-static bool radeon_device_is_virtual(void)
+bool radeon_device_is_virtual(void)
 {
 #ifdef CONFIG_X86
 	return boot_cpu_has(X86_FEATURE_HYPERVISOR);