arm64: dts: qcom: sm8450: enable GCC_USB3_0_CLKREF_EN for usb

USB doesn't work at all without this clock enabled. This fixes USB when not
using clk_ignore_unused.

Fixes: 19fd04fb ("arm64: dts: qcom: sm8450: Add usb nodes")
Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220122162932.7686-1-jonathan@marek.ca