drm/amdgpu:fix firmware memoryleak(v2)

this fix memory leak due to request_firmware after driver
unloaded

v2:
release gmc firmware for gmc6/7/8 as well

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
index e028286..447d446 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
@@ -92,6 +92,12 @@ static int psp_sw_init(void *handle)
 
 static int psp_sw_fini(void *handle)
 {
+	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
+
+	release_firmware(adev->psp.sos_fw);
+	adev->psp.sos_fw = NULL;
+	release_firmware(adev->psp.asd_fw);
+	adev->psp.asd_fw = NULL;
 	return 0;
 }