arm: socfpga: Add clock for smp_twd timer

Assign a clock for the twd-timer.
Signed-off-by: Dinh Nguyen <dinguyen@altera.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Ian Campbell <ian.campbell@citrix.com>
CC: linux-arm-kernel@lists.infradead.org

arch/arm/boot/dts/socfpga.dtsi

@@ -473,6 +473,7 @@ timer@fffec600 {
 			compatible = "arm,cortex-a9-twd-timer";
 			reg = <0xfffec600 0x100>;
 			interrupts = <1 13 0xf04>;
+			clocks = <&mpu_periph_clk>;
 		};
 
 		timer0: timer0@ffc08000 {