usb: gadget: tegra-xudc: Remove unneeded return variable

The 'ret' variable in the function tegra_xudc_gadget_vbus_draw() is not
needed and so remove this variable.

Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20230405181854.42355-2-jonathanh@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>