document: board: mimxrt1170_evk add SAI support
document: board: mimxrt1170_evk add SAI support

add information for SAI module

Signed-off-by: Hake Huang <141c0384c6b2febca367ae94dc4dc40a33a7ba79@oss.nxp.com>

zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr