This moves the variable assignments previously done in /env/config-board
to non volatile variables in /env/nv/. This makes the settings adjustable
by the user without editing a file.

Most of the changes are simple conversions which for many boards makes
/env/config-board unnecessary. Some boards had some logic to assign
global.boot.default based on the current bootsource. This has been
moved to /env/init/bootsource. An additional check is added to not
overwrite a nv.boot.default should it exist.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Rename the barebox_loc environment variable to bootsource, since
- barebox_loc is a mixture between abbriviation and fulltext which is not nice
- technically it describes the source the SoC has booted from. This is not
  necessarily barebox but could also be some other first stage loader.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

The Efika MX Smartbook is a i.MX51 based netbook. This patch adds
nearly full support for it including:

- USB
- SD card slots
- Internal SPI NOR flash
- Internal flash PATA drive
- LEDs

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>