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/20211210120201.35635-1-andriy.shevchenko@linux.intel.comSigned-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

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>