drm/i915: wire up CRC interrupt for ilk/snb

We enable the interrupt unconditionally and only control it
through the enable bit in the CRC control register.

v2: Extract per-platform helpers to compute the register values.

Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 11bd8b2..8b1f2db 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3918,12 +3918,14 @@
 #define DE_PIPEB_ODD_FIELD      (1 << 13)
 #define DE_PIPEB_LINE_COMPARE   (1 << 12)
 #define DE_PIPEB_VSYNC          (1 << 11)
+#define DE_PIPEB_CRC_DONE	(1 << 10)
 #define DE_PIPEB_FIFO_UNDERRUN  (1 << 8)
 #define DE_PIPEA_VBLANK         (1 << 7)
 #define DE_PIPEA_EVEN_FIELD     (1 << 6)
 #define DE_PIPEA_ODD_FIELD      (1 << 5)
 #define DE_PIPEA_LINE_COMPARE   (1 << 4)
 #define DE_PIPEA_VSYNC          (1 << 3)
+#define DE_PIPEA_CRC_DONE	(1 << 2)
 #define DE_PIPEA_FIFO_UNDERRUN  (1 << 0)
 
 /* More Ivybridge lolz */