s3c2410fb: multi-display support

This patch adds a new structure to describe and handle
more than one panel (display mode) for the s3c2410 framebuffer.
This structure is added after the pxafb driver.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>