util: add SMPTE pattern support for C1 format

util: add SMPTE pattern support for C1 format

Add support for drawing the SMPTE pattern in a buffer using the C1
indexed format.

As only two colors are available, the pattern is drawn in black and
white, using Floyd-Steinberg dithering[1].

[1] https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dithering

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
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Dithering example at https://drive.google.com/file/d/1waJczErrIaEKRhBCCU1ynxRG8agpo0Xx/view

v5:
  - Add Reviewed-by,

v4:
  - Replace FILL_COLOR() use by bw_color_lut[],

v3:
  - Add Acked-by,
  - Add Wikipedia link,

v2:
  New.