clk: imx: Remove the audio ipg clock from imx8mp

There is no audio ipg clock on i.MX8MP, so remove this from
the clock driver.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>