treewide: drop shebang from non-executable lib files

This drops the shebang from another bunch of files in various /lib
folders, as these are sourced and the shebang is useless.

Fix execute bit in one case, too.

This should cover almost all trivial cases now, i.e. where /lib is
actually used for library files.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

package/base-files/files/lib/functions/leds.sh

@@ -1,4 +1,3 @@
-#!/bin/sh
 # Copyright (C) 2013 OpenWrt.org
 
 get_dt_led_path() {

package/base-files/files/lib/functions/migrations.sh

@@ -1,5 +1,3 @@
-#!/bin/sh
-
 . /lib/functions.sh
 
 migrate_led_sysfs() {

package/base-files/files/lib/functions/preinit.sh

@@ -1,4 +1,3 @@
-#!/bin/sh
 # Copyright (C) 2006-2013 OpenWrt.org
 # Copyright (C) 2010 Vertical Communications
 

package/base-files/files/lib/functions/uci-defaults.sh

@@ -1,5 +1,3 @@
-#!/bin/ash
-
 . /lib/functions.sh
 . /usr/share/libubox/jshn.sh