drm/amdgpu: fix regression in vbios reservation handling on headless

We need to move the check under the non-headless case, otherwise
we always reserve the VGA save size.

Fixes: 157fe68d ("drm/amdgpu: fix size calculation with stolen vga memory")
Reviewed-by: NGuchun Chen <guchun.chen@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -496,13 +496,14 @@ void amdgpu_gmc_get_vbios_allocations(struct amdgpu_device *adev)
 		break;
 	}
 
-	if (!amdgpu_device_ip_get_ip_block(adev, AMD_IP_BLOCK_TYPE_DCE))
+	if (!amdgpu_device_ip_get_ip_block(adev, AMD_IP_BLOCK_TYPE_DCE)) {
 		size = 0;
-	else
+	} else {
 		size = amdgpu_gmc_get_vbios_fb_size(adev);
 
-	if (adev->mman.keep_stolen_vga_memory)
-		size = max(size, (unsigned)AMDGPU_VBIOS_VGA_ALLOCATION);
+		if (adev->mman.keep_stolen_vga_memory)
+			size = max(size, (unsigned)AMDGPU_VBIOS_VGA_ALLOCATION);
+	}
 
 	/* set to 0 if the pre-OS buffer uses up most of vram */
 	if ((adev->gmc.real_vram_size - size) < (8 * 1024 * 1024))