mediatek: replace multiple fw_setenv calls by the bulk one

This commit replaces multiple fw_setenv calls by the bulk one to reduce
flash writes.

Thanks @Linaro1985 for the idea.

Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>
Link: openwrt#17580
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/mediatek/filogic/base-files/lib/upgrade/platform.sh

@@ -40,13 +40,15 @@ xiaomi_initial_setup()
 		return 0
 	fi
 
-	fw_setenv boot_wait on
-	fw_setenv uart_en 1
-	fw_setenv flag_boot_rootfs 0
-	fw_setenv flag_last_success 1
-	fw_setenv flag_boot_success 1
-	fw_setenv flag_try_sys1_failed 8
-	fw_setenv flag_try_sys2_failed 8
+	fw_setenv -s - <<-EOF
+		boot_wait on
+		uart_en 1
+		flag_boot_rootfs 0
+		flag_last_success 1
+		flag_boot_success 1
+		flag_try_sys1_failed 8
+		flag_try_sys2_failed 8
+	EOF
 
 	local board=$(board_name)
 	case "$board" in