i2c: Constify i2c_client where possible

Helper functions for I2C and SMBus transactions don't modify the
i2c_client that is passed to them, so it can be marked const.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index d827ce5..0d559b6 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -106,9 +106,9 @@
 	struct i2c_client	*client;
 	struct rtc_device	*rtc;
 	struct work_struct	work;
-	s32 (*read_block_data)(struct i2c_client *client, u8 command,
+	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
 			       u8 length, u8 *values);
-	s32 (*write_block_data)(struct i2c_client *client, u8 command,
+	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
 				u8 length, const u8 *values);
 };
 
@@ -158,8 +158,8 @@
 
 #define BLOCK_DATA_MAX_TRIES 10
 
-static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
-				  u8 length, u8 *values)
+static s32 ds1307_read_block_data_once(const struct i2c_client *client,
+				       u8 command, u8 length, u8 *values)
 {
 	s32 i, data;
 
@@ -172,7 +172,7 @@
 	return i;
 }
 
-static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
+static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
 				  u8 length, u8 *values)
 {
 	u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
@@ -198,7 +198,7 @@
 	return length;
 }
 
-static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
+static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
 				   u8 length, const u8 *values)
 {
 	u8 currvalues[I2C_SMBUS_BLOCK_MAX];