MI_STORE_REGISTER_MEM, MI_LOAD_REGISTER_MEM, and MI_LOAD_REGISTER_IMM
commands allow userspace access to registers. Only certain registers
should be allowed for such access, so enable checking for those commands.
Each ring gets its own register whitelist.

MI_LOAD_REGISTER_REG on HSW also allows register access but is currently
unused by userspace components. Leave it rejected.

PIPE_CONTROL and MEDIA_VFE_STATE allow register access based on certain
bits being set. Reject those as well.

v2: trailing commas, rebased

OTC-Tracker: AXIA-4631
Change-Id: Ie614a2f0eb2e5917de809e5a17957175d24cc44f
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>