arm64: dts: qcom: sm8350: Fix DSI PLL size

As downstream indicates, DSI PLL is actually 0x27c and not 0x260-
wide. Fix that to reserve the correct registers.

Fixes: d4a44105 ("arm64: dts: qcom: sm8350: Add display system nodes")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230120210101.2146852-6-konrad.dybcio@linaro.org