drm/i915: Add register whitelists for mesa

These registers are currently used by mesa for blitting,
transform feedback extensions, and performance monitoring
extensions.

v2: REG64 macro

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>