drm/xe: Move xe_mmio_probe_tiles outside of MMIO setup

MMIO is going to be setup earlier during probe. Move xe_mmio_probe_tiles
outside of MMIO setup.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20231129214509.1174116-6-michal.winiarski@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>