fix a series of Documentation/ broken file name references

As files move around, their previous links break. Fix the
references for them.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>

drivers/sbus/char/oradax.c

@@ -30,7 +30,7 @@
  * the recommended way for applications to use the coprocessor, and
  * the driver interface is not intended for general use.
  *
- * See Documentation/sparc/oradax/oracle_dax.txt for more details.
+ * See Documentation/sparc/oradax/oracle-dax.txt for more details.
  */
 
 #include <linux/uaccess.h>