ARM: dts: sh73a0: Rename twd clock to periph clock

The "TWD" clock is actually the Cortex-A9 MPCore "PERIPHCLK" clock,
which not only clocks the private timers and watchdogs (TWD), but also
the interrupt controller and global timer.

Hence rename it from "twd" to "periph".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191211135222.26770-2-geert+renesas@glider.be

arch/arm/boot/dts/sh73a0.dtsi

@@ -43,7 +43,7 @@ timer@f0000600 {
 		compatible = "arm,cortex-a9-twd-timer";
 		reg = <0xf0000600 0x20>;
 		interrupts = <GIC_PPI 13 (GIC_CPU_MASK_SIMPLE(2) | IRQ_TYPE_EDGE_RISING)>;
-		clocks = <&twd_clk>;
+		clocks = <&periph_clk>;
 	};
 
 	gic: interrupt-controller@f0001000 {
@@ -812,7 +812,7 @@ pll1_div13_clk: pll1_div13 {
 			clock-div = <13>;
 			clock-mult = <1>;
 		};
-		twd_clk: twd {
+		periph_clk: periph {
 			compatible = "fixed-factor-clock";
 			clocks = <&cpg_clocks SH73A0_CLK_Z>;
 			#clock-cells = <0>;