drm/bridge: cdns: prepare for drmP.h removal from drm_modeset_helper.h

The use of drmP.h is discouraged and removal of it from
drm_modeset_helper.h caused cdns to fail to build.

This patch introduce the necessary fixes to prepare for the
drmP.h removal from drm_modeset_helper.h.

Build tested on arm x86 and arm allmodconfig.

Signed-off-by: Sam Ravnborg <[e-mail]>
Cc: Andrzej Hajda <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/bridge/cdns-dsi.c

···
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_drv.h>
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_panel.h>
 #include <video/mipi_display.h>
 
 #include <linux/clk.h>
+#include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of_address.h>