i2c: i2c-stm32f7: make structure stm32f7_setup static const

The structure stm32f7_setup is local to the source and does not need
to be in global scope, make it static const.

Cleans up sparse warning:
symbol 'stm32f7_setup' was not declared. Should it be static?
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NPierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-stm32f7.c

@@ -265,7 +265,7 @@ static struct stm32f7_i2c_spec i2c_specs[] = {
 	},
 };
 
-struct stm32f7_i2c_setup stm32f7_setup = {
+static const struct stm32f7_i2c_setup stm32f7_setup = {
 	.rise_time = STM32F7_I2C_RISE_TIME_DEFAULT,
 	.fall_time = STM32F7_I2C_FALL_TIME_DEFAULT,
 	.dnf = STM32F7_I2C_DNF_DEFAULT,