mips: io.h: delete duplicated word

Delete the repeated word "on".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/include/asm/io.h

@@ -59,7 +59,7 @@
  * which all ports are being mapped.  For sake of efficiency some code
  * assumes that this is an address that can be loaded with a single lui
  * instruction, so the lower 16 bits must be zero.  Should be true on
- * on any sane architecture; generic code does not use this assumption.
+ * any sane architecture; generic code does not use this assumption.
  */
 extern unsigned long mips_io_port_base;