arm64: dts: qcom: msm8996: remove snps,dw-pcie compatibles

On MSM8996 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: ed965ef8 ("arm64: dts: qcom: msm8996: add support to pcie")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>