drm/i915: Move Haswell registers to separate whitelist table

Now that we can whitelist registers only on Haswell, move HSW_SCRATCH1
and HSW_ROW_CHICKEN3 into a separate Haswell only table.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Cc: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1457335830-30923-4-git-send-email-jordan.l.justen@intel.com