drm/xe/pf: Don't attempt to process FAST_REQ or EVENT relays

drm/xe/pf: Don't attempt to process FAST_REQ or EVENT relays

Currently defined VF/PF relay actions use regular REQUEST messages
only and the PF shouldn't attempt to handle FAST_REQUEST nor EVENT
messages as this would result in breaking the VFPF ABI protocol
and also might trigger an assert on the PF side.

Fixes: 98e62805921c ("drm/xe/pf: Add SR-IOV GuC Relay PF services")
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patch.msgid.link/20260527183735.22616-1-michal.wajdeczko@intel.com