drm/logicvc: Fix preferred fbdev cpp

Logicvc can have different values for the preferred color depth. Set
the fbdev bpp value depending on the runtime value.

v2:
	* remove unused color depth of 15 from switch (Javier)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20221123115348.2521-3-tzimmermann@suse.de

drivers/gpu/drm/logicvc/logicvc_drm.c

@@ -301,6 +301,7 @@ static int logicvc_drm_probe(struct platform_device *pdev)
 	struct regmap *regmap = NULL;
 	struct resource res;
 	void __iomem *base;
+	unsigned int preferred_bpp;
 	int irq;
 	int ret;
 
@@ -438,7 +439,17 @@ static int logicvc_drm_probe(struct platform_device *pdev)
 		goto error_mode;
 	}
 
-	drm_fbdev_generic_setup(drm_dev, drm_dev->mode_config.preferred_depth);
+	switch (drm_dev->mode_config.preferred_depth) {
+	case 16:
+		preferred_bpp = 16;
+		break;
+	case 24:
+	case 32:
+	default:
+		preferred_bpp = 32;
+		break;
+	}
+	drm_fbdev_generic_setup(drm_dev, preferred_bpp);
 
 	return 0;