Supports all bpp modes.

The PRTCON register is used to disable in-hardware updates of registers
that store start and end addresses of framebuffer memory.  This prevents
display corruption in case we do not make it before VSYNC with updating
them atomically.  With this feature there is no need to wait for a VSYNC
interrupt before each such update.
Signed-off-by: NPawel Osciak <p.osciak@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Cc: InKi Dae <inki.dae@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>