parisc: decode_exc.c should include kernel.h

Fix this build error:
arch/parisc/math-emu/decode_exc.c:351: undefined reference to `printk'
Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/math-emu/decode_exc.c

@@ -40,7 +40,7 @@
  * END_DESC
 */
 
-
+#include <linux/kernel.h>
 #include "float.h"
 #include "sgl_float.h"
 #include "dbl_float.h"