'struct i2c_device_id' is not modified in this driver.

Constifying this structure moves some data to a read-only section, so
increase overall security.

While at it, also add some space to be consistent with cs42l51_of_match a
few lines below.

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   1551	    384	     16	   1951	    79f	sound/soc/codecs/cs42l51-i2c.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   1631	    304	     16	   1951	    79f	sound/soc/codecs/cs42l51-i2c.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Compile tested-only.
---
 sound/soc/codecs/cs42l51-i2c.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/soc/codecs/cs42l51-i2c.c b/sound/soc/codecs/cs42l51-i2c.c
index e7cc50096297..f171bd66fcac 100644
--- a/sound/soc/codecs/cs42l51-i2c.c
+++ b/sound/soc/codecs/cs42l51-i2c.c
@@ -13,9 +13,9 @@
 
 #include "cs42l51.h"
 
-static struct i2c_device_id cs42l51_i2c_id[] = {
-	{"cs42l51"},
-	{}
+static const struct i2c_device_id cs42l51_i2c_id[] = {
+	{ "cs42l51" },
+	{ }
 };
 MODULE_DEVICE_TABLE(i2c, cs42l51_i2c_id);
 
-- 
2.47.0