arc770: gen_axs10x_sdcard_img.sh: switch to /bin/sh

Nothing here needs bash.

Signed-off-by: Rosen Penev <[email protected]>
[add prefix to commit title]
Signed-off-by: Adrian Schmutzler <[email protected]>

target/linux/arc770/image/gen_axs10x_sdcard_img.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 #
 # Copyright (C) 2016 OpenWrt.org