clk: qcom: gcc-sc8280xp: Add missing GDSC flags

All of the 8280's GCC GDSCs can and should use the retain registers so
as not to lose their state when entering lower power modes.

Fixes: d65d005f ("clk: qcom: add sc8280xp GCC driver")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20230620-topic-sc8280_gccgdsc-v2-1-562c1428c10d@linaro.org


Signed-off-by: Bjorn Andersson <andersson@kernel.org>