vgacon: remove unneeded forward declarations

[ Upstream commit 6ceed69c ]

Most of the forward declarations in vgacon are not needed. Drop them.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Helge Deller <deller@gmx.de>
Stable-dep-of: 03bcbbb3 ("dummycon: Trigger redraw when switching consoles with deferred takeover")
Signed-off-by: Sasha Levin <sashal@kernel.org>