drm/xe/vf: Store the GuC FW info in guc->fw

drm/xe/vf: Store the GuC FW info in guc->fw

The GuC compatibility version that we read from the CSS header in
native/PF and the GuC VF version that we get when a VF handshakes with
the GuC are the same version number, so we should store it into the same
structure. This makes all the checks based on the compatibility version
automatically work for VFs without having to copy the value over.

For completion, also copy the wanted version and set the path to a known
string to indicate that the FW is PF-loaded. This way all the info will
be coherent when dumped from debugfs.

v2: several code cleanups and style changes (Michal), rebase on
bootstrap changes.

v3: s/min/wanted/, clarify that handshake must happen before we can get
the VF versions (Michal)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lukasz Laguna <lukasz.laguna@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://lore.kernel.org/r/20250603235432.720833-10-daniele.ceraolospurio@intel.com