drm/amd: Use suspend and hibernate post freeze notifications

commit 2965e63 ("drm/amd: Add Suspend/Hibernate notification
callback support") introduced a VRAM eviction earlier in the PM
sequences when swap was still available for evicting to. This helped
to fix a number of memory pressure related bugs but also exposed a
new one.

If a userspace process is actively using the GPU when suspend starts
then a deadlock could occur.

Instead of going off the prepare notifier, use the PM notifiers that
occur after processes have been frozen to do evictions.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4178
Fixes: 2965e63 ("drm/amd: Add Suspend/Hibernate notification callback support")
Signed-off-by: Mario Limonciello <[email protected]>

Author: superm1

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -4842,10 +4842,10 @@ static int amdgpu_device_pm_notifier(struct notifier_block *nb, unsigned long mo
 	int r;
 
 	switch (mode) {
-	case PM_HIBERNATION_PREPARE:
+	case PM_HIBERNATION_POST_FREEZE:
 		adev->in_s4 = true;
 		fallthrough;
-	case PM_SUSPEND_PREPARE:
+	case PM_SUSPEND_POST_FREEZE:
 		r = amdgpu_device_evict_resources(adev);
 		/*
 		 * This is considered non-fatal at this time because