drm/amdgpu: Fix APU handling in amdgpu_pm_load_smu_firmware()

We only need to skip this on modern APUs.  It's required
on older APUs as it's where start_smu gets called from.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3502
Fixes: 064d9243 ("drm/amd/pm: avoid to load smu firmware for APUs")
Reviewed-by: Tim Huang <tim.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Tim Huang <Tim.Huang@amd.com>
(cherry picked from commit 608d886c)

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

@@ -618,7 +618,8 @@ int amdgpu_pm_load_smu_firmware(struct amdgpu_device *adev, uint32_t *smu_versio
 	const struct amd_pm_funcs *pp_funcs = adev->powerplay.pp_funcs;
 	int r = 0;
 
-	if (!pp_funcs || !pp_funcs->load_firmware || adev->flags & AMD_IS_APU)
+	if (!pp_funcs || !pp_funcs->load_firmware ||
+	    (is_support_sw_smu(adev) && (adev->flags & AMD_IS_APU)))
 		return 0;
 
 	mutex_lock(&adev->pm.mutex);