drm/i915: crc support for hsw

hw designers decided to change the CRC registers and coalesce them all
into one. Otherwise nothing changed. I've opted for a new hsw_ version
to grab the crc sample since hsw+1 will have the same crc registers,
but different interrupt source registers. So this little helper
function will come handy there.

Also refactor the display error handler with a neat pipe loop.

v2: Use for_each_pipe.

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 8b1f2db..0e7488b 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -728,6 +728,7 @@
 #define   ERR_INT_PIPE_CRC_DONE_B	(1<<5)
 #define   ERR_INT_FIFO_UNDERRUN_B	(1<<3)
 #define   ERR_INT_PIPE_CRC_DONE_A	(1<<2)
+#define   ERR_INT_PIPE_CRC_DONE(pipe)	(1<<(2 + pipe*3))
 #define   ERR_INT_FIFO_UNDERRUN_A	(1<<0)
 #define   ERR_INT_FIFO_UNDERRUN(pipe)	(1<<(pipe*3))