ARM: tegra: pinctrl: make pmux_func values consistent on Tegra20

ARM: tegra: pinctrl: make pmux_func values consistent on Tegra20

For consistency with other SoCs, modify Tegra20's enum pmux_func to:

* Remove PMUX_FUNC values that aren't real
* Use the same PMUX_FUNC_RSVD[1-4] values, and ensure (RSVD1 & 3)==0;
  this will be assumed by pinmux_set_func() in a future patch.

Unfortunately, PMUX_FUNC_RSVD is still used in the pin macros. Use a
private define inside the driver to prevent this from causing compilaton
errors. This will be cleaned up when the pin tables are re-written in a
later patch in this series.

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