drm: include only needed headers in ascii85.h

The ascii85.h is user of exactly two headers, i.e.  math.h and types.h.
There is no need to carry on entire kernel.h.

Link: https://lkml.kernel.org/r/20210611185915.44181-1-andriy.shevchenko@linux.intel.comSigned-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/ascii85.h

@@ -8,7 +8,8 @@
 #ifndef _ASCII85_H_
 #define _ASCII85_H_
 
-#include <linux/kernel.h>
+#include <linux/math.h>
+#include <linux/types.h>
 
 #define ASCII85_BUFSZ 6