omap: gen_omap_sdcard_img.sh: use /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/omap/image/gen_omap_sdcard_img.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 #
 # Copyright (C) 2013 OpenWrt.org