pinmux: stm32f4: Add STM32_OSPEEDR_VERY_HIGH_SPEED to pinmux header

Since STM32_OSPEEDR_VERY_HIGH_SPEED flag is required for all I2S_CK
pins, lets add this to the STM32F4 pinmux header and remove the
duplicates in board files. While we are at it, let's add the missing
pinmux definitions for I2S_2 also.

Fixes: #9028

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>