arm64: dts: rockchip: add fastboot mode for rk3308

Enable fastboot when reboot command with fastboot.

Change-Id: I6a00700a014d5bd04eaf4980779bf89edc352426
Signed-off-by: zain wang <wzz@rock-chips.com>

Author: zainwangrockchips

arch/arm64/boot/dts/rockchip/rk3308.dtsi

@@ -312,6 +312,7 @@
 			mode-loader = <BOOT_BL_DOWNLOAD>;
 			mode-normal = <BOOT_NORMAL>;
 			mode-recovery = <BOOT_RECOVERY>;
+			mode-fastboot = <BOOT_FASTBOOT>;
 		};
 	};