The single channel detection in the gazerbeam board driver was not
implemented correctly.

Fix the detection.

Signed-off-by: Mario Six <mario.six@gdsys.cc>

Complete in the drivers directory the work started with
commit 83d290c56fab ("SPDX: Convert all of our single
license tags to Linux Kernel style").

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

Add tests for the new board uclass.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>

Add a board driver for the upcoming gdsys Gazerbeam board.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>

Since there is no canonical "board device" that can be used in board
files, it is difficult to use DM function for board initialization in
these cases.

Hence, add a uclass that implements a simple "board device", which can
hold devices not suitable anywhere else in the device tree, and is also
able to read encoded information, e.g. hard-wired GPIOs on a GPIO
expander, read-only memory ICs, etc. that carry information about the
hardware.

The devices of this uclass expose methods to read generic data types
(integers, strings, booleans) to encode the information provided by the
hardware.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>