drm/omap: dsi: Fix crash in DSI debug dumps

Reading any of the DSI debugfs files results in a crash, as wrong
pointer is passed to the dump functions, and the dump functions use a
wrong pointer. This patch fixes DSI debug dumps.

Fixes: f3ed97f9

 ("drm/omap: dsi: Simplify debugfs implementation")
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111035120.20668-3-laurent.pinchart@ideasonboard.com