kernel: add phtotnicat2 power management driver

This add the photonicat2 power management driver and the necessary
device trees nodes to monitor battery, charging status and pwmfan.
Then mount them to sysfs.
The c files was imported from the photonocat official
openwrt sdk patchfile and lack detailed commit message.

Signed-off-by: Jason Zou <jasonforhise@outlook.com>

package/kernel/photonicat-pm/Makefile

@@ -0,0 +1,29 @@
+include $(TOPDIR)/rules.mk
+include $(INCLUDE_DIR)/kernel.mk
+
+PKG_NAME:=photonicat-pm
+PKG_RELEASE:=1
+
+PKG_LICENSE:=GPL-2.0-or-later
+
+include $(INCLUDE_DIR)/package.mk
+
+define KernelPackage/photonicat-pm
+  SUBMENU:=Other modules
+  TITLE:=Photonicat Power Manager
+  FILES:=$(PKG_BUILD_DIR)/photonicat-pm.ko
+  AUTOLOAD:=$(call AutoLoad,60,photonicat-pm,1)
+  DEPENDS:= @TARGET_rockchip_armv8 +kmod-hwmon-core +kmod-thermal 
+  KCONFIG:= 
+endef
+
+define KernelPackage/photonicat-pm/description
+  Power manager for photonicat board.
+  Unless you have the platform, you will want to say 'N'.
+endef
+
+define Build/Compile
+	$(KERNEL_MAKE) M="$(PKG_BUILD_DIR)" modules
+endef
+
+$(eval $(call KernelPackage,photonicat-pm))

package/kernel/photonicat-pm/src/Makefile

@@ -0,0 +1 @@
+obj-m += photonicat-pm.o

target/linux/rockchip/files/arch/arm64/boot/dts/rockchip/rk3576-photonicat2.dts

@@ -981,6 +981,9 @@
 		charger {
 			monitored-battery = <&battery>;
 		};
+
+		fan {
+		};
 	};
 };