drm/i915/error: drop dmesg suggestion to file bugs on GPU hangs

drm/i915/error: drop dmesg suggestion to file bugs on GPU hangs

We haven't updated the DRIVER_TIMESTAMP since commit 3570bd989acc
("drm/i915: Update DRIVER_DATE to 20230929") 1½ years ago. Before then,
the previous update was commit 139caf7ca286 ("drm/i915: Update
DRIVER_DATE to 20201103") 4+ years ago. The DRIVER_DATE has also been
removed altogether.

We've used the DRIVER_TIMESTAMP to log suggestions to file bugs on GPU
hangs when they happen on a driver less than six months old. Combined
with the sporadic DRIVER_TIMESTAMP updates, we really haven't logged the
suggestions for years.

Just stop logging the suggestion to file bugs altogether, and remove
DRIVER_TIMESTAMP. This doesn't really change anything wrt to logging GPU
errors or how we handle bugs. And effectively we already stopped logging
the message a year ago when we stopped updating DRIVER_TIMESTAMP.

Instead, add an unconditional message about the GPU error state
location.

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Link: https://lore.kernel.org/r/20250429115055.2133143-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>