Add poky-agl-next.inc file to hold temporary next branch over-rides,
and include it in poky-agl.conf. For now it just over-rides the
AGL_BRANCH value for agl-service-gps to use the next branch.
This can be removed once the next branches containing zeus support
are merged into master.
Bug-AGL: SPEC-2932
Change-Id: Id73597c6f35010e4e5f9b54ac09728c7783b9e2f
Signed-off-by: Scott Murray <scott.murray@konsulko.com>