drm/amdgpu: Avoid fetching vram vendor information

For GFX 9.4.3 APUs, the current method of fetching vram vendor
information is not reliable. Avoid fetching the information.

Signed-off-by: Lijo Lazar <[e-mail]>
Reviewed-by: Hawking Zhang <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c

···
 	static const u32 regBIF_BIOS_SCRATCH_4 = 0x50;
 	u32 vram_info;
 
-	if (!amdgpu_sriov_vf(adev)) {
+	/* Only for dGPU, vendor informaton is reliable */
+	if (!amdgpu_sriov_vf(adev) && !(adev->flags & AMD_IS_APU)) {
 		vram_info = RREG32(regBIF_BIOS_SCRATCH_4);
 		adev->gmc.vram_vendor = vram_info & 0xF;
 	}