drm/amdgpu: fix warning on older gcc releases

gcc-4.8 warns about '{0}' being used an an initializer for nested structures:

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c: In function ‘gfx_v8_0_ring_emit_ce_meta_init’:
drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c:7263:2: warning: missing braces around initializer [-Wmissing-braces]
  } ce_payload = {0};
drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c: In function ‘gfx_v8_0_ring_emit_de_meta_init’:
drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c:7290:2: warning: missing braces around initializer [-Wmissing-braces]
  } de_payload = {0};

Using an empty {} initializer however has the same effect and works on all versions.

Fixes: acad2b2a7b70 ("drm/amdgpu:implement CE/DE meta-init routines")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c

@@ -7268,7 +7268,7 @@ static void gfx_v8_0_ring_emit_ce_meta_init(struct amdgpu_ring *ring, uint64_t c
 	static union {
 		struct amdgpu_ce_ib_state regular;
 		struct amdgpu_ce_ib_state_chained_ib chained;
-	} ce_payload = {0};
+	} ce_payload = {};
 
 	if (ring->adev->virt.chained_ib_support) {
 		ce_payload_addr = csa_addr + offsetof(struct amdgpu_gfx_meta_data_chained_ib, ce_payload);
@@ -7295,7 +7295,7 @@ static void gfx_v8_0_ring_emit_de_meta_init(struct amdgpu_ring *ring, uint64_t c
 	static union {
 		struct amdgpu_de_ib_state regular;
 		struct amdgpu_de_ib_state_chained_ib chained;
-	} de_payload = {0};
+	} de_payload = {};
 
 	gds_addr = csa_addr + 4096;
 	if (ring->adev->virt.chained_ib_support) {