ARM: dts: qcom: apq8064: Use 27MHz PXO clock as DSI PLL reference

ARM: dts: qcom: apq8064: Use 27MHz PXO clock as DSI PLL reference

The 28NM DSI PLL driver for msm8960 calculates with a 27MHz reference
clock and should hence use PXO, not CXO which runs at 19.2MHz.

Note that none of the DSI PHY/PLL drivers currently use this "ref"
clock; they all rely on (sometimes inexistant) global clock names and
usually function normally without a parent clock.  This discrepancy will
be corrected in a future patch, for which this change needs to be in
place first.

Fixes: 4250c1441a0d ("ARM: dts: qcom-apq8064: Set 'cxo_board' as ref clock of the DSI PHY")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Link: https://lore.kernel.org/r/20210829203027.276143-2-marijn.suijten@somainline.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>