drm/panel: otm8009a: Switch to mipi_dsi_multi_context helpers

drm/panel: otm8009a: Switch to mipi_dsi_multi_context helpers

Update the driver to use the non-deprecated mipi_dsi_*_multi()
helpers, as recommended in Documentation/gpu/todo.rst. The multi
variants provide proper error accumulation and handle the required
DCS NOP insertions, which suits the OTM8009A command sequences.

Refactor otm8009a_dcs_write_buf() and the dcs_write_seq/dcs_write_cmd_at
macros to take a mipi_dsi_multi_context pointer, passing it through
from callers. This ensures consistent error handling throughout the
driver.

Replace all mdelay() and msleep() calls within DSI command sequences
with mipi_dsi_msleep() for proper error accumulation.

The init, disable, and backlight update paths now return dsi_ctx.accum_err,
ensuring errors are propagated to callers.

Signed-off-by: Amin GATTOUT <amin.gattout@gmail.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20251213142421.6762-1-amin.gattout@gmail.com