ARM: dts: qcom: msm8974: add correct XO clock source to GCC node

Change the XO clock in MSM8974's GCC node to point to RPMCC.

Signed-off-by: Rayyan Ansari <rayyan@ansari.sh>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230121192540.9177-4-rayyan@ansari.sh