fbdev: add the carmine FB driver

Basic FB driver for the carmine chip.  The driver registers two FB devices for
the two possible screens.  The DRAM settings can be be switched via Kconfig
(between eval board and custom).

Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>