ia64, scsi: update references for the device-io book

The book is now at Documentation/driver-api/device-io.rst.
Update such references.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/arch/ia64/include/asm/io.h b/arch/ia64/include/asm/io.h
index 5de673a..a2540e2 100644
--- a/arch/ia64/include/asm/io.h
+++ b/arch/ia64/include/asm/io.h
@@ -117,7 +117,7 @@ extern int valid_mmap_phys_addr_range (unsigned long pfn, size_t count);
  * following the barrier will arrive after all previous writes.  For most
  * ia64 platforms, this is a simple 'mf.a' instruction.
  *
- * See Documentation/DocBook/deviceiobook.tmpl for more information.
+ * See Documentation/driver-api/device-io.rst for more information.
  */
 static inline void ___ia64_mmiowb(void)
 {