default.xml: pin meta-rpb to commit right before RPM becomes the default
default.xml: pin meta-rpb to commit right before RPM becomes the default

Don't use RPM as the package format until this is fixed:
https://github.com/96boards/meta-96boards/issues/156
(it brakes all 64-bit builds which use mali or powervr or any other
similar userland graphics driver which is single library file with
a bunch of synlinks to it)

Signed-off-by: Andrey Konovalov <6decb425dd3212bf9b96628630c2d12a43fdad79@linaro.org>

linaro-home/lhg-oe-manifests