arm64: dts: imx8mq-librem5-devkit: Drop custom clock settings

arm64: dts: imx8mq-librem5-devkit: Drop custom clock settings

Otherwise the boot hangs early on and the resulting clock tree without
this already closely matches the selected rates (722534400 and
786432000).

  audio_pll2                  0        0        0   722534397          0     0  50000
     audio_pll2_bypass        0        0        0   722534397          0     0  50000
        audio_pll2_out        0        0        0   722534397          0     0  50000
  audio_pll1                  1        1        0   786431998          0     0  50000
     audio_pll1_bypass        1        1        0   786431998          0     0  50000
        audio_pll1_out        1        1        0   786431998          0     0  50000
           sai2               1        1        0    24576000          0     0  50000
              sai2_root_clk       1        1        0    24576000          0     0  50000
           sai6               0        0        0    24576000          0     0  50000
              sai6_root_clk       0        0        0    24576000          0     0  50000

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>