Add macro fdt_for_each_node_by_compatible() to allow iterating over
fdt nodes by compatible string.

Convert various usages of
    off = fdt_node_offset_by_compatible(fdt, start, compat);
    while (off > 0) {
        code();
        off = fdt_node_offset_by_compatible(fdt, off, compat);
    }
and similar, to
    fdt_for_each_node_by_compatible(off, fdt, start, compat)
        code();

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

This adds video output support for Amlogic GXBB/GXL/GXM chips.
The supported ports are CVBS and HDMI (based on DW_HDMI).

When using HDMI, only DMT modes are supported.

There is support for simple-framebuffer (CONFIG_VIDEO_DT_SIMPLEFB)

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Jorge Ramire-Ortiz <jramirez@baylibre.com>
Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
[narmstrong: fixed defines alignment in meson_canvas.c]
Reviewed-by: Anatolij Gustschin <agust@denx.de>