drm/xe/guc: Reduce default GuC log verbosity

Drop the default verbosity from 5 (max) to 3 as the extra verbosity
generally doesn't provide anything vitally important but does cause
rapid log overflow.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241108212737.2044007-2-John.C.Harrison@Intel.com