staging: greybus: es2: Use kmemdup instead of kmalloc and memcpy

This patch replaces kmalloc and memcpy with kmemdup for duplication of
memory.

Signed-off-by: sayli karnik <karniksayli1995@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>