arm64: dts: qcom: msm8996: Make CPUCC actually probe (and work)

Fix the compatible to make the driver probe and tell the
driver where to look for the "xo" clock to make sure everything
works.

Then we get a happy (eh, happier) 8996:

somainline-sdcard:/home/konrad# cat /sys/kernel/debug/clk/pwrcl_pll/clk_rate
1152000000

Don't backport without "arm64: dts: qcom: msm8996: Add CPU opps", as
the system fails to boot without consumers for these clocks.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Link: https://lore.kernel.org/r/20210527192958.775434-1-konrad.dybcio@somainline.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>