dietpi-installer: use current branch for mainline on RK35xx

Also assign correct NanoPi Zero2 device tree in that case and simplify ZSTD compressed initramfs logic, not that all supported kernel versions support it.

Author: MichaIng

.build/images/dietpi-installer

@@ -728,7 +728,7 @@ setenv rootuuid "true"' /boot/boot.cmd
 						esac
 					;;
 					85) G_CONFIG_INJECT 'fdtfile=' 'fdtfile=rockchip/rk3588s-rock-5a.dtb' /boot/dietpiEnv.txt;;
-					104) G_CONFIG_INJECT 'fdtfile=' 'fdtfile=rockchip/rk3528-nanopi-rev01.dtb' /boot/dietpiEnv.txt;;
+					104) [[ $RK35XX_MAINLINE == 1 ]] && G_CONFIG_INJECT 'fdtfile=' 'fdtfile=rockchip/rk3528-nanopi-zero2.dtb' /boot/dietpiEnv.txt || G_CONFIG_INJECT 'fdtfile=' 'fdtfile=rockchip/rk3528-nanopi-rev01.dtb' /boot/dietpiEnv.txt;;
 					*) :;;
 				esac
 				# Overlay prefix
@@ -1189,7 +1189,7 @@ _EOF_
 			esac
 
 			# Override with mainline kernel if wanted
-			[[ $RK35XX_MAINLINE == 1 && $kernel == 'rk35xx' ]] && kernel='rockchip64' branch='edge'
+			[[ $RK35XX_MAINLINE == 1 && $kernel == 'rk35xx' ]] && kernel='rockchip64' branch='current'
 
 			# NanoPi R2S/NEO3
 			if [[ $G_HW_MODEL =~ ^(55|56)$ ]]
@@ -1225,10 +1225,9 @@ fi' /boot/boot.cmd
 			/boot/dietpi/func/dietpi-set_software apt clean
 			G_AGUP
 
-			# Install initramfs-tools first to have an initramfs generated on kernel install, and configure it to use zstd if supported for better compression and faster decompression
-			[[ $kernel == 's5p6818' ]] || zstd=('zstd')
-			G_AGI initramfs-tools u-boot-tools armbian-firmware "${zstd[@]}"
-			[[ ${zstd[0]} ]] && G_CONFIG_INJECT 'COMPRESS=' 'COMPRESS=zstd' /etc/initramfs-tools/initramfs.conf
+			# Install initramfs-tools first to have an initramfs generated on kernel install, and configure it to use zstd for better compression and faster decompression
+			G_AGI initramfs-tools zstd armbian-firmware u-boot-tools
+			G_CONFIG_INJECT 'COMPRESS=' 'COMPRESS=zstd' /etc/initramfs-tools/initramfs.conf
 
 			# Install testing kernel build if requested
 			if (( $TEST_KERNEL ))