kdumpctl: change the shebang header to use /bin/bash

We met one issue that when changing softlink of "/usr/bin/sh"
to point to "ksh" instead of the default "bash", kdumpctl will
not work and go wrong.

kdumpctl is expected to run under bash like dracut, we should
change its shebang header from "#!/bin/sh" to "#!/bin/bash".

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>

kdumpctl

@@ -1,4 +1,4 @@
-#! /bin/sh
+#!/bin/bash
 KEXEC=/sbin/kexec
 
 KDUMP_KERNELVER=""