ASoC: fsl_xcvr: refine the requested phy clock frequency

As the input phy clock frequency will divided by 2 by default
on i.MX8MP with the implementation of clk-imx8mp-audiomix driver,
So the requested frequency need to be updated.

The relation of phy clock is:
    sai_pll_ref_sel
       sai_pll
          sai_pll_bypass
             sai_pll_out
                sai_pll_out_div2
                   earc_phy_cg

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Link: https://lore.kernel.org/r/1700702093-8008-1-git-send-email-shengjiu.wang@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>