drm/i915/dg2: Add preemption changes for Wa_14015141709

drm/i915/dg2: Add preemption changes for Wa_14015141709

Starting with DG2, preemption can no longer be controlled using userspace
on a per-context basis. Instead, the hardware only allows us to enable or
disable preemption in a global, system-wide basis.  Also, we lose the
ability to specify the preemption granularity (such as batch-level vs
command-level vs object-level).

v2 (MattR):
 - Move debugfs interface to a separate patch.  (Jani)
v3 (MattR):
 - Drop the debugfs support completely for now.

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>
Cc: John Harrison <john.c.harrison@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220318021051.2073847-1-matthew.d.roper@intel.com