gpiolib: make names array and its values const

gpiolib doesn't need to modify the names and I assume most initializers
use string constants that shouldn't be modified anyhow.

[akpm@linux-foundation.org: fix drivers/gpio/cs5535-gpio.c]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Kevin Wells <kevin.wells@nxp.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index f156ab3..a2b12aa 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -73,7 +73,7 @@
 	struct i2c_client *client;
 	struct pca953x_platform_data *dyn_pdata;
 	struct gpio_chip gpio_chip;
-	char **names;
+	const char *const *names;
 };
 
 static int pca953x_write_reg(struct pca953x_chip *chip, int reg, uint16_t val)