MIPS: fix typo in a comment

The double `Address' in the comment in line 487 is repeated. Remove one
of them from the comment.
Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/include/asm/sibyte/sb1250_mc.h

@@ -484,7 +484,7 @@
 
 
 /*
- * Bank Address Address Bits Register (Table 6-22)
+ * Bank Address Bits Register (Table 6-22)
  */
 
 #define S_MC_BA_RESERVED	    0