Reset color attributes and clear screen when starting up

Some boot loaders, like GRUB, leave background color artifacts from
their boot menu.  This patch resets the foreground and background
color attributes, and then clears the screen, without clearing the
scrollback buffer.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/helpers.c

@@ -87,6 +87,9 @@ void console_init(void)
 	/* Enable line wrap, if disabled previously, e.g., qemu */
 	dprint(STDOUT_FILENO, "\033[?7h", 5);
 
+	/* Reset atttributes, background and foreground color  */
+	dprint(STDOUT_FILENO, "\033[49m\033[39m\e[2J", 14);
+
 	log_init();
 }