upstart: Move MACHINE specific configuration to upstart-getty

* MACHINE specific upstart is causing different checksums for a lot
  do_package tasks, move MACHINE specific variables to upstart-getty
  and exclude it from SIGGEN
* use webos_upstartconfdir variable

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Change-Id: I09831d3c4790ac7205d72887af1339de7b47f04d
Reviewed-on: https://g2g.palm.com/1856
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Steve Lemke <steve.lemke@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
upstart: Use webos_upstartconfdir variable

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Change-Id: I491098543a3a00fc085cf6684e43086fd55bff6c
Reviewed-on: https://g2g.palm.com/1857
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>