arm64: dts: qcom: sm8250: remove snps,dw-pcie compatibles

On SM8250 PCI controller bindings are not compatible with snps,dw-pcie
binding. The platform doesn't provide second (global) IRQ, it requires
additional glue code. To prevent it from probing against the dw-pcie
driver, remove corresponding compatible.

Fixes: e53bdfc0 ("arm64: dts: qcom: sm8250: Add PCIe support")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>