drm/i915: Whitelist COMMON_SLICE_CHICKEN3 for UMD access

A recommended tuning setting for both gen12 and Xe_HP platforms requires
that we grant userspace r/w access to the COMMON_SLICE_CHICKEN3
register.

Bspec: 73993, 73994, 31870, 68331
Cc: Dongwon Kim <dongwon.kim@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230224002300.3578985-1-matthew.d.roper@intel.com