i2c: stm32f7: rework slave_id allocation

The IP can handle two slave addresses. One address can either be
7 bits or 10 bits while the other can only be 7 bits.
In order to ensure that a 10 bits address can always be allocated
(assuming there is only one 7 bits address already allocated),
pick up the 7-bits only address slot in priority when performing a 7-bits
address allocation.

Fixes: 60d609f ("i2c: i2c-stm32f7: Add slave support")
Signed-off-by: Alain Volmat <alain.volmat@st.com>
Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-stm32f7.c

@@ -1265,7 +1265,7 @@ static int stm32f7_i2c_get_free_slave_id(struct stm32f7_i2c_dev *i2c_dev,
 	 * slave[0] supports 7-bit and 10-bit slave address
 	 * slave[1] supports 7-bit slave address only
 	 */
-	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+	for (i = STM32F7_I2C_MAX_SLAVE - 1; i >= 0; i--) {
 		if (i == 1 && (slave->flags & I2C_CLIENT_PEC))
 			continue;
 		if (!i2c_dev->slave[i]) {