At least I couldn't find it in the Haswell Bspec any more and we've
tried to test-boot a Haswell machine with num_pipes forced to 0 (i.e.
hit the PCH_NOP path) and the unclaimed register logic complained.
So restrict this dance to just ivb platforms.
v2: Art pointed out that the bits simply moved on hsw+
v3: Buy code terseneness with a notch of sublety as suggested by
Chris.
v4: Frob the right bit, spotted by Art.
Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Arthur Ranyan <arthur.j.runyan@intel.com> Cc: Dave Airlie <airlied@gmail.com> Reviewed-by: Art Runyan <arthur.j.runyan@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>