media: dmxdev: drop unneeded <linux/kernel.h> inclusion from other headers

There is no evidence we need kernel.h inclusion in certain headers.
Drop unneeded <linux/kernel.h> inclusion from other headers.

Link: https://lore.kernel.org/linux-media/[email protected]
Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

Author: andy-shev

include/media/dmxdev.h

@@ -21,7 +21,6 @@
 
 #include <linux/types.h>
 #include <linux/spinlock.h>
-#include <linux/kernel.h>
 #include <linux/time.h>
 #include <linux/timer.h>
 #include <linux/wait.h>