Adds a parameter which can be used with DRM_I915_GETPARAM to query the
GPU revision. The intention is to use this in Mesa to implement the
WaDisableSIMD16On3SrcInstr workaround on Skylake but only for
revision 2.
Signed-off-by: Neil Roberts <neil@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>