drm/amdgpu/irq: check if nbio funcs exist

We need to check if the nbios funcs exist before
checking the individual pointers.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>

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

@@ -159,10 +159,12 @@ irqreturn_t amdgpu_irq_handler(int irq, void *arg)
 	 * register to check whether the interrupt is triggered or not, and properly
 	 * ack the interrupt if it is there
 	 */
-	if (adev->nbio.funcs->handle_ras_controller_intr_no_bifring)
+	if (adev->nbio.funcs &&
+	    adev->nbio.funcs->handle_ras_controller_intr_no_bifring)
 		adev->nbio.funcs->handle_ras_controller_intr_no_bifring(adev);
 
-	if (adev->nbio.funcs->handle_ras_err_event_athub_intr_no_bifring)
+	if (adev->nbio.funcs &&
+	    adev->nbio.funcs->handle_ras_err_event_athub_intr_no_bifring)
 		adev->nbio.funcs->handle_ras_err_event_athub_intr_no_bifring(adev);
 
 	return ret;