usb: gadget: tegra-xudc: Fix USB3 PHY retrieval logic

This commit resolves an issue in the tegra-xudc USB gadget driver that
incorrectly fetched USB3 PHY instances. The problem stemmed from the
assumption of a one-to-one correspondence between USB2 and USB3 PHY
names and their association with physical USB ports in the device tree.

Previously, the driver associated USB3 PHY names directly with the USB3
instance number, leading to mismatches when mapping the physical USB
ports. For instance, if using USB3-1 PHY, the driver expect the
corresponding PHY name as 'usb3-1'. However, the physical USB ports in
the device tree were designated as USB2-0 and USB3-0 as we only have
one device controller, causing a misalignment.

This commit rectifies the issue by adjusting the PHY naming logic.
Now, the driver correctly correlates the USB2 and USB3 PHY instances,
allowing the USB2-0 and USB3-1 PHYs to form a physical USB port pair
while accurately reflecting their configuration in the device tree by
naming them USB2-0 and USB3-0, respectively.

The change ensures that the PHY and PHY names align appropriately,
resolving the mismatch between physical USB ports and their associated
names in the device tree.

Fixes: b4e19931

 ("usb: gadget: tegra-xudc: Support multiple device modes")
Cc: stable@vger.kernel.org
Signed-off-by: Wayne Chang <waynec@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20240307030328.1487748-3-waynec@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>