pinctrl: tegra: reduce size of data table fields

The range of npins and function ID values is small enough to fit into a
u8. Use this type rather than unsigned to shrink the pinmux data tables.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>