initscripts: let populate-volatile.sh create the /tmp link

initscripts: let populate-volatile.sh create the /tmp link

Previously, the /tmp link (/tmp -> /var/tmp) was created by the
bootmisc.sh script. So in case of a read-only rootfs, this symlink
would not be created correctly.

The populate-volatile.sh script is intended to handle all directories
and files related to volatile storage, so we should let it create
the /tmp link.

In addition, because of the improments of populate-volatile.sh, the data
loss problem of bug#3404 is also resolved by this patch.

[YOCTO #3406]
[YOCTO #3404]

(From OE-Core rev: 12c4acd7ac5a27cf3676065b60f1c8395c96854c)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>