drm/panel: jdi-lpm102a188a: Fix error code in jdi_panel_prepare()

If the mipi_dsi_dual() macro fails, the error code is stored in
dsi_ctx.accum_err. Propagate that error back to the caller instead
of returning success as the current code does.

Fixes: a6adf47d30cc ("drm/panel: jdi-lpm102a188a: Fix bug and clean up driver")
Signed-off-by: Dan Carpenter <[e-mail]>
Reviewed-by: Douglas Anderson <[e-mail]>
Signed-off-by: Douglas Anderson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c

···
 	mipi_dsi_dual(mipi_dsi_dcs_set_display_on_multi,
 		      &dsi_ctx, jdi->link1, jdi->link2);
 
-	if (dsi_ctx.accum_err < 0)
+	if (dsi_ctx.accum_err < 0) {
+		err = dsi_ctx.accum_err;
 		goto poweroff;
+	}
 
 	jdi->link1->mode_flags &= ~MIPI_DSI_MODE_LPM;
 	jdi->link2->mode_flags &= ~MIPI_DSI_MODE_LPM;