linux-yocto-tiny_3.17: Update to actually use 3.17 git repo

The named release was still using the -dev git repo which did not contain
the SRCREV referenced in the numbered/named version.

(From OE-Core rev: b4f2f39c)

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>