Add xuser to disk group, so it could write usb storage in which the
filesystem type is vfat/fat.
[YOCTO #4004]
(From OE-Core rev: 07a969443bc3cdd3799aa7f04aa5aac2cbdd00e8)
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>