rsi: make array fsm_state static const, makes object smaller

Don't populate the array fsm_state on the stack but instead it
static const. Makes the object code smaller by 154 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
   9213	   3904	      0	  13117	   333d	.../wireless/rsi/rsi_91x_debugfs.o

After:
   text	   data	    bss	    dec	    hex	filename
   8995	   3968	      0	  12963	   32a3	.../wireless/rsi/rsi_91x_debugfs.o

(gcc version 10.3.0)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210819125018.8577-1-colin.king@canonical.com

drivers/net/wireless/rsi/rsi_91x_debugfs.c

@@ -117,7 +117,7 @@ static int rsi_stats_read(struct seq_file *seq, void *data)
 {
 	struct rsi_common *common = seq->private;
 
-	unsigned char fsm_state[][32] = {
+	static const unsigned char fsm_state[][32] = {
 		"FSM_FW_NOT_LOADED",
 		"FSM_CARD_NOT_READY",
 		"FSM_COMMON_DEV_PARAMS_SENT",