usb: dwc3: qcom: Detect DWC3 DT-nodes using compatible string

usb: dwc3: qcom: Detect DWC3 DT-nodes using compatible string

In accordance with the USB HCD/DRD schema all the USB controllers are
supposed to have DT-nodes named with prefix "^usb(@.*)?". Since the
existing DT-nodes will be renamed in a subsequent patch let's fix the DWC3
Qcom-specific code to detect the DWC3 sub-node just by checking its
compatible string to match the "snps,dwc3". The semantic of the code
won't change seeing all the DWC USB3 nodes are supposed to have the
compatible property with any of those strings set.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210409113029.7144-7-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>