fbcon: Silence fbcon logo on 'quiet' boots

On text-based systems the 'quiet' boot option will show printk levels
higher than CONSOLE_LOGLEVEL_QUIET. The displaying of the Tux logo
during boot can cause some consoles to lose display data and as a result
confuse the end user.

Do not display the Tux logo on systems that are in 'quiet' boot.

v2: It helps to commit all my changes before sending them. Remove extra
bracket.
v3: buildbot error fix: fbcon can be built as part of a module so export console_printk
v4: move console_printk change to separate patch, and drop logo cleanup
v5: Only set FBCON_LOGO_DONTSHOW for console loglevel

Signed-off-by: Prarit Bhargava <[e-mail]>
Cc: Hans de Goede <[e-mail]>
Cc: Marko Myllynen <[e-mail]>
Cc: Steven Rostedt (VMware) <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Thierry Reding <[e-mail]>
Cc: Yisheng Xie <[e-mail]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[e-mail]>

drivers/video/fbdev/core/fbcon.c

···
 		kfree(save);
 	}
 
+	if (logo_shown == FBCON_LOGO_DONTSHOW)
+		return;
+
 	if (logo_lines > vc->vc_bottom) {
 		logo_shown = FBCON_LOGO_CANSHOW;
 		printk(KERN_INFO
 		       "fbcon_init: disable boot-logo (boot-logo bigger than screen).\n");
-	} else if (logo_shown != FBCON_LOGO_DONTSHOW) {
+	} else {
 		logo_shown = FBCON_LOGO_DRAW;
 		vc->vc_top = logo_lines;
 	}
···
 	    return;
 
 	cap = info->flags;
+
+	if (console_loglevel <= CONSOLE_LOGLEVEL_QUIET)
+		logo_shown = FBCON_LOGO_DONTSHOW;
 
 	if (vc != svc || logo_shown == FBCON_LOGO_DONTSHOW ||
 	    (info->fix.type == FB_TYPE_TEXT))