clk: qcom: gcc-msm8998: Remove transient global "xo" clock

clk: qcom: gcc-msm8998: Remove transient global "xo" clock

Now that all clock controllers and the DSI PLL clocks rely on "xo" being
passed in DT as phandle instead of looking it up by the global "xo" name
this transient clock can be removed, leaving only the fixed-factor
"xo_board" clock in DT.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Link: https://lore.kernel.org/r/20210911121340.261920-4-marijn.suijten@somainline.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>