ARM: tegra: Remove pre-pinctrl pinmux driver

The pinctrl driver is now active and used by all boards. Remove the
old pinmux driver.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>