[PATCH] fbcon: Console Rotation - Add framebuffer console documentation

Add documentation as Documentation/fb/fbcon.txt describing the framebuffer
console and its boot options.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>