yajl: Use SRCREV

* this recipe is not using webos_enhanced_submissions
  let it use SRCREV directly like every other upstream
  recipe

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Change-Id: I83f63a53017c9d32d8b558e3ab83e5a4c0c8ff97
Reviewed-on: https://g2g.palm.com/1997
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Herb Kuta <herb.kuta@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>