clk: qcom: gcc-sc7280: Update the .pwrsts for PCIe GDSC

Enabling PCIe GDSC retention to ensure controller and its
dependent clocks won't go down during system suspend.
Update the .pwrsts for PCIe GDSC so it only transitions
to RET in low power.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/1663669347-29308-6-git-send-email-quic_krichai@quicinc.com