sstate: Revert using -m option to tar in sstate
In http://git.yoctoproject.org/cgit.cgi/poky/commit/?id=
2d89cff42af2bb0049224bfaaebaa2b21966169f
we added a workaround for dealing with lack of time sync between build
machines and their users.
This has turned out to cause problems for people who rely on timestamps
being preserved in sstate output.
Since our autobuilders are all in time sync with ntp, revert the commit.
[YOCTO #8996]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
