arm64: dts: qcom: sc7280: Use GIC_SPI for intc cells

Let's use the GIC_SPI macro instead of a plain 0 here to match other
uses of the primary interrupt controller on sc7280.

Suggested-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Alex Elder <elder@linaro.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210811181904.779316-1-swboyd@chromium.org