drm/msm/sde: add preliminary debugfs support

Debugfs additions under /sys/kernel/debug/dri/0.

Add sde_debugfs_setup_regset32()/sde_debugfs_create_regset32()
for creating register dump debugfs files, and add initial debugfs
support in plane driver.

Change-Id: I7e0a368fbcf6a249a016d2224c01666fe51abae9
Signed-off-by: Clarence Ip <cip@codeaurora.org>
diff --git a/drivers/gpu/drm/msm/sde/sde_hw_pingpong.c b/drivers/gpu/drm/msm/sde/sde_hw_pingpong.c
index e678003..49a98be 100644
--- a/drivers/gpu/drm/msm/sde/sde_hw_pingpong.c
+++ b/drivers/gpu/drm/msm/sde/sde_hw_pingpong.c
@@ -48,6 +48,7 @@
 			b->base_off = addr;
 			b->blk_off = m->pingpong[i].base;
 			b->hwversion = m->hwversion;
+			b->log_mask = SDE_DBG_MASK_PINGPONG;
 			return &m->pingpong[i];
 		}
 	}