i2c: constify internal structures

Check for i2c_algorithm and i2c_adapter_quirks structures that are only
stored in the algo and quirks fields of an i2c_adapter structure
correspondingly. These fields are declared const, so i2c_algorithm and
i2c_adapter_quirks structures that have this property can be declared
as const also.

Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> (for designware)
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
index 0548c7e..60a7977 100644
--- a/drivers/i2c/busses/i2c-designware-slave.c
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -343,7 +343,7 @@ static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
 	return IRQ_RETVAL(ret);
 }
 
-static struct i2c_algorithm i2c_dw_algo = {
+static const struct i2c_algorithm i2c_dw_algo = {
 	.functionality = i2c_dw_func,
 	.reg_slave = i2c_dw_reg_slave,
 	.unreg_slave = i2c_dw_unreg_slave,