util/reserved-region: Add new ReservedRegion helpers

util/reserved-region: Add new ReservedRegion helpers

Introduce resv_region_list_insert() helper which inserts
a new ReservedRegion into a sorted list of reserved region.
In case of overlap, the new region has higher priority and
hides the existing overlapped segments. If the overlap is
partial, new regions are created for parts which are not
overlapped. The new region has higher priority independently
on the type of the regions.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Tested-by: Yanghang Liu <yanghliu@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>