ath5k: constify stuff

Make some structures const to place them in .rodata, since we won't
change them.

Most important parts of objdump -h:
-  0 .text         00011170
+  0 .text         00011140
-  5 .rodata       0000828e
+  5 .rodata       0000895e
- 13 .data         00000560
+ 13 .data         00000110
- 14 .devinit.data 00000260

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Bob Copeland <me@bobcopeland.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath5k/reset.c

@@ -102,7 +102,7 @@ static inline int ath5k_hw_write_ofdm_timings(struct ath5k_hw *ah,
  * index into rates for control rates, we can set it up like this because
  * this is only used for AR5212 and we know it supports G mode
  */
-static int control_rates[] =
+static const unsigned int control_rates[] =
 	{ 0, 1, 1, 1, 4, 4, 6, 6, 8, 8, 8, 8 };
 
 /**