arm64: dts: qcom: sm6125: Switch fixed xo_board clock to RPM XO clock

arm64: dts: qcom: sm6125: Switch fixed xo_board clock to RPM XO clock

We have a working RPM XO clock; no other driver except rpmcc should be
parenting directly to the fixed-factor xo_board clock nor should it be
reachable by that global name.  Remove the name to that effect, so that
every clock relation is explicitly defined in DTS.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Link: https://lore.kernel.org/r/20230723-sm6125-dpu-v4-14-a3f287dd6c07@somainline.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>