arm64: dts: meson: enable rtc node on Khadas VIM1/VIM2 boards

Enable the rtc node on VIM1/VIM2 boards so users can simply attach a power
cell and use the on-board RTC without modifying the device-tree.

Cold boot with no cell attached is gracefully handled:

VIM2:~ # dmesg | grep rtc
[    7.716150] rtc-hym8563 1-0051: no valid clock/calendar values available
[    7.716957] rtc-hym8563 1-0051: registered as rtc0
[    7.729850] rtc-hym8563 1-0051: no valid clock/calendar values available
[    7.729877] rtc-hym8563 1-0051: hctosys: unable to read the hardware clock
[    8.126768] rtc-hym8563 1-0051: no valid clock/calendar values available

Warm boot (and any boot with cell attached) recalls stored values resulting
in consistently faster (re)boot times:

VIM2:~ # dmesg | grep rtc
[    7.441671] rtc-hym8563 1-0051: registered as rtc0
[    7.442663] rtc-hym8563 1-0051: setting system clock to 2020-11-16T05:49:59 UTC (1605505799)

Suggested-by: Artem Lapkin <[email protected]>
Signed-off-by: Christian Hewitt <[email protected]>
Reviewed-by: Neil Armstrong <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

arch/arm64/boot/dts/amlogic/meson-gxl-s905x-khadas-vim.dts

@@ -97,8 +97,7 @@
 	pinctrl-names = "default";
 
 	rtc: rtc@51 {
-		/* has to be enabled manually when a battery is connected: */
-		status = "disabled";
+		status = "okay";
 		compatible = "haoyu,hym8563";
 		reg = <0x51>;
 		#clock-cells = <0>;

arch/arm64/boot/dts/amlogic/meson-gxm-khadas-vim2.dts

@@ -228,8 +228,7 @@
 	pinctrl-names = "default";
 
 	rtc: rtc@51 {
-		/* has to be enabled manually when a battery is connected: */
-		status = "disabled";
+		status = "okay";
 		compatible = "haoyu,hym8563";
 		reg = <0x51>;
 		#clock-cells = <0>;