gbm: Don't pass default usage flags on ABIs < 1
Older drivers will not expect any flags from the GBM front-end when modifiers are in use, and will likely fail the allocation or handle them incorrectly as a result. Only specify usage flags when allocating from a backend with an ABI >= 1, as that's the ABI version that added support for specifying usage flags along with modifiers.
Fixes: ad50b47a ("gbm: assume USE_SCANOUT in create_with_modifiers")
Closes: #5709 (closed)