media: stih-cec: add missing io.h

In the driver the io.h is implied by others.  This is not good as it
prevents from cleanups done in other headers.  Add missing include.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Andy Shevchenko <[email protected]>
Cc: Alain Volmat <[email protected]>
Cc: AngeloGioacchino Del Regno <[email protected]>
Cc: Chen-Yu Tsai <[email protected]>
Cc: Hans Verkuil <[email protected]>
Cc: Jernej Skrabec <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Patrice Chotard <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Samuel Holland <[email protected]>
Cc: Sean Wang <[email protected]>
Cc: Sean Young <[email protected]>
Cc: Stefani Seibold <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

drivers/media/cec/platform/sti/stih-cec.c

@@ -6,6 +6,7 @@
  */
 #include <linux/clk.h>
 #include <linux/interrupt.h>
+#include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>