This converts the Tegra SPI drivers to use driver model. This is tested
on:

- Tegra20 - trimslice
- Tegra30 - beaver
- Tegra124 - dalmore

(not tested on Tegra124)
Reviewed-by: NJagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
Signed-off-by: NSimon Glass <sjg@chromium.org>