drm/amd/pm: refine amdgpu pm sysfs node error code

v1:
Returns different error codes based on the scenario to help the user app understand
the AMDGPU device status when an exception occurs.

v2:
change -NODEV to -EBUSY.

Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Yang Wang

drivers/gpu/drm/amd/pm/amdgpu_pm.c

@@ -110,9 +110,10 @@ static int amdgpu_pm_dev_state_check(struct amdgpu_device *adev, bool runpm)
 	bool runpm_check = runpm ? adev->in_runpm : false;
 
 	if (amdgpu_in_reset(adev))
-		return -EPERM;
+		return -EBUSY;
+
 	if (adev->in_suspend && !runpm_check)
-		return -EPERM;
+		return -EBUSY;
 
 	return 0;
 }