drm/amd/amdgpu/amdgpu_fw_attestation: Consume our own header containing prototypes

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/amdgpu_fw_attestation.c:130:6: warning: no previous prototype for ‘amdgpu_fw_attestation_debugfs_init’ [-Wmissing-prototypes]

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Hawking Zhang <Hawking.Zhang@amd.com>
Cc: John Clements <john.clements@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -26,6 +26,7 @@
 #include <linux/dma-mapping.h>
 
 #include "amdgpu.h"
+#include "amdgpu_fw_attestation.h"
 #include "amdgpu_psp.h"
 #include "amdgpu_ucode.h"
 #include "soc15_common.h"
@@ -139,4 +140,4 @@ void amdgpu_fw_attestation_debugfs_init(struct amdgpu_device *adev)
 			    adev,
 			    &amdgpu_fw_attestation_debugfs_ops);
 #endif
-}
+}