fbdev/mb862xxfb: Output messages with fb_dbg()

Fix cases were output helpers are called with struct fb_info.dev.
Use fb_dbg() instead. Prepares fbdev for making struct fb_info.dev
optional.

v2:
	* fix another reference to struct fb_info.dev (kernel test reobot)
	* remove fb_err() from commit message
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230613110953.24176-17-tzimmermann@suse.de

drivers/video/fbdev/mb862xx/mb862xxfbdrv.c

@@ -112,8 +112,7 @@ static int mb862xxfb_check_var(struct fb_var_screeninfo *var,
 {
 	unsigned long tmp;
 
-	if (fbi->dev)
-		dev_dbg(fbi->dev, "%s\n", __func__);
+	fb_dbg(fbi, "%s\n", __func__);
 
 	/* check if these values fit into the registers */
 	if (var->hsync_len > 255 || var->vsync_len > 255)
@@ -290,7 +289,7 @@ static int mb862xxfb_blank(int mode, struct fb_info *fbi)
 	struct mb862xxfb_par  *par = fbi->par;
 	unsigned long reg;
 
-	dev_dbg(fbi->dev, "blank mode=%d\n", mode);
+	fb_dbg(fbi, "blank mode=%d\n", mode);
 
 	switch (mode) {
 	case FB_BLANK_POWERDOWN:
@@ -791,7 +790,7 @@ static void of_platform_mb862xx_remove(struct platform_device *ofdev)
 	resource_size_t res_size = resource_size(par->res);
 	unsigned long reg;
 
-	dev_dbg(fbi->dev, "%s release\n", fbi->fix.id);
+	fb_dbg(fbi, "%s release\n", fbi->fix.id);
 
 	/* display off */
 	reg = inreg(disp, GC_DCM1);
@@ -1138,7 +1137,7 @@ static void mb862xx_pci_remove(struct pci_dev *pdev)
 	struct mb862xxfb_par *par = fbi->par;
 	unsigned long reg;
 
-	dev_dbg(fbi->dev, "%s release\n", fbi->fix.id);
+	fb_dbg(fbi, "%s release\n", fbi->fix.id);
 
 	/* display off */
 	reg = inreg(disp, GC_DCM1);