drm/xe: Initialize GuC earlier during probe

SR-IOV VF has limited access to MMIO registers. Fortunately, it is able
to access a curated subset that is needed to initialize the driver by
communicating with SR-IOV PF using GuC CT.
Initialize GuC earlier in order to keep the unified probe ordering
between VF and PF modes.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219130530.1406044-4-michal.winiarski@intel.com