gpu/arm: don't execute probe asynchronously

When we select an asynchronous probe type, sometimes the device can be stuck when we execute the initialization sequence (kbase_device_init).

This regression has been introduced by the last update:

96acbfbdca2e gpu/arm: update midgard driver to r32p0 release

If we let the default probe type, we don't see this issue anymore.

Fixes RITY-280