drivers: i2c: stm32 I2C v2 driver fix compliance with a Macro

Define Macro to fix the compliance check warning :
"DEEP_INDENTATION: Too many leading tabs - consider code refactoring
in the i2c_compute_scll_sclh() function
in the i2c_compute_presc_scldel_sdadel() function

Signed-off-by: Francois Ramu <francois.ramu@st.com>