ARM: tegra: add port FF to GPIO IDs

NVIDIA Tegra124 supports has the new GPIO port as GPIO_FF.
Add the macro for this port name.

Signed-off-by: Ashwini Ghuge <aghuge@nvidia.com>
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>