amdgpu: detect if we are using atomfirmware or atombios for vbios (v2)

Supposedly atomfirmware rom header is 3.3 atombios is 1.1.

v2: rebased on newer kernel

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1308,6 +1308,7 @@ struct amdgpu_device {
 	bool				have_disp_power_ref;
 
 	/* BIOS */
+	bool				is_atom_fw;
 	uint8_t				*bios;
 	uint32_t			bios_size;
 	struct amdgpu_bo		*stollen_vga_memory;