drm/i915/gt: Move snb GT workarounds from init_clock_gating to workarounds

drm/i915/gt: Move snb GT workarounds from init_clock_gating to workarounds

Rescue the GT workarounds from being buried inside init_clock_gating so
that we remember to apply them after a GT reset, and that they are
included in our verification that the workarounds are applied.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20200611080140.30228-4-chris@chris-wilson.co.uk
(cherry picked from commit c3b93a943f2c9ee4a106db100a2fc3b2f126bfc5)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>