drm/i915: No need for RING_MAX_NONPRIV_SLOTS space

Now that we write RING_FORCE_TO_NONPRIV registers directly to hardware,
[commit 32ced39c ("drm/i915: Transform whitelisting WAs into a simple reg
write")] there is no need to save space for them in the list of context
workarounds.

v2: Refer to previous commit in commit message (Michel)

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1508272071-15125-1-git-send-email-oscar.mateo@intel.com


Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>