tegra: seaboard: Correct the gpio_request() call

Requesting a GPIO without a name is not supposed anymore. This causes the
request to fail. Add a name so that the serial console works on seaboard.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>