drm/meson: Fix OSD1 RGB to YCbCr coefficient

VPP_WRAP_OSD1_MATRIX_COEF22.Coeff22 is documented as being bits 0-12,
not 16-28.

Without this the output tends to have a pink hue, changing it results
in better color accuracy.

The vendor kernel doesn't use this register. However the code which
sets VIU2_OSD1_MATRIX_COEF22 also uses bits 0-12. There is a slightly
different style of registers for configuring some of the other matrices,
which do use bits 16-28 for this coefficient, but those have names
ending in MATRIX_COEF22_30, and this is not one of those.

Signed-off-by: Stuart Menefy <stuart.menefy@mathembedded.com>
Fixes: 72888394 ("drm/meson: Add G12A Support for VIU setup")
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220908155243.687143-1-stuart.menefy@mathembedded.com