sstate.bbclass: Don't create symlinks, download to the correct location
Previously the sstate was all downloaded to the same directory and then
symlinks were added in the directories that pointed to the siginfo and
sstate in the parent directory.
This change makes it so that now the files are just downloaded to the
correct location without the need for symlinks.
Signed-off-by: Randy Witt <randy.e.witt@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
