We use 'priv' for private data but often use 'platdata' for platform data.
We can't really use 'pdata' since that is ambiguous (it could mean private
or platform data).

Rename some of the latter variables to end with 'plat' for consistency.

Signed-off-by: Simon Glass <sjg@chromium.org>

To make the button command useful in a shell script it should return the
status of the button:

* 0 (true) - pressed, on
* 1 (false) - not pressed, off

The button command takes only one argument. Correct maxargs.

Adjust the Python unit test.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Philippe Reynes <philippe.reynes@softathome.com>

Adds a command 'button' that provides the list of buttons
supported by the board, and the state of a button.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>