clk: qcom: gcc-sc7180: Update the .pwrsts for usb gdsc

The USB controller on sc7180 does not retain the state when
the system goes into low power state and the GDSC is
turned off. This results in the controller reinitializing and
re-enumerating all the connected devices (resulting in additional
delay while coming out of suspend)
Fix this by updating the .pwrsts for the USB GDSC so it only
transitions to retention state in low power.
Since sc7180 only supports cx (parent of usb gdsc) Retention, there
are no cxcs offsets mentioned in order to support the Retention
state.

Signed-off-by: Rajendra Nayak <quic_rjendra@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220920111517.10407-2-quic_rjendra@quicinc.com