drivers: clock control of stm32f4 serie w/o clk 48M on PLL I2S

Some stm32f4, like the sm32f411 mcu have clk 48M on the main PLL output q
Some stm32f4, like the sm32f412 mcu have clk 48M on the PLL I2S output q
This PR is for selecting the right one

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