clk: imx: imx8mp: correct DISP2 pixel clock type

The MEDIA_DISP2_CLK_ROOT use ccm_ahb_channel, it is bus type.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20230403094633.3366446-1-peng.fan@oss.nxp.com


Signed-off-by: Abel Vesa <abel.vesa@linaro.org>