build-tfm: Provisioning in memory over rom

RSS now uses provisioning bundles loaded to volatile memory. Previously
these were loaded in one bundle in the ROM.

There are now two bundles cm_provisioning_bundle and dm_provisioning
bundle which are for vm0 and vm1 respectively.

Signed-off-by: Joel Goddard <joel.goddard@arm.com>
Change-Id: I0f6c7b492713e4ffb7a47cc7a1354cd13cc61f59