mojolocation-stub: Simplify by inheriting webos_system_bus

:Release Notes:
The recent enhancements to webos_system_bus.bbclass allow it be to used
by this recipe.

:Detailed Notes:

:Testing Performed:
Confirmed that the contents of the packages are unchanged.

:QA Notes:

:Issues Addressed:
[GF-9954] webos_system_bus: Allow installation of system bus files from
          ${S}/files/sysbus

Open-webOS-DCO-1.0-Signed-off-by: Herb Kuta <herb.kuta@lge.com>
Change-Id: Ide1cbea0c3e544a2b6e3e3169c4574f5c1e2819c
Reviewed-on: https://g2g.palm.com/2880
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
Tested-by: Susan Montooth <susan.montooth@lge.com>