ARM: tegra: allow custom usb manufacturer/product/vendor ids/strings

Allow for optional custom USB gadget manufacturer/product/vendor
IDs/strings to be specified.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>