ARM: dts: exynos: Correct DWC USB3 compatible string

Syonpsys IP cores are supposed to be defined with "snps" vendor-prefix.
Use it instead of the deprecated "synopsys" one.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201020115959.2658-5-Sergey.Semin@baikalelectronics.ru


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>