os/board/rtl8730e: add driver layer implemenation for i2s tdm

Add initial porting/os layer commit
- TDM parameters fixed on I2S2 to generate required signal for AIS25BA
- DMA is not tested and likely requires further implementation

Config:
- RTL8730E Peripheral Support:
    [ ] AMEBASMART_I2C
    [*] Amebasmart I2S
    [*] I2S_2
    [*] Enable I2S RX
    [*] Enable I2S TDM Support
- Device Drivers:
    [ ] I2C Driver Support
    [*] I2S Driver Support
- Application Configuration > Examples:
    [*] I2S character driver test
    [*] Use I2S receiver
    [ ] Use I2S transmitter
    /dev/i2schar4 I2S character device path