Fix: tools: crm_resource --set-parameter works with master resources

Previously, the command failed because it used the clone element from
the post-schema-upgrade CIB as the basis for certain CIB operations. We
need to use the master element from the original, pre-upgrade CIB
instead.

Also, we can assume that cib != NULL in update_element_attribute().

Ref T885.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>