Allocate the framebuffer memory as coherent, otherwise the framebuffer
will suffer from artifacts when displaying scrolling text or video.
This can be replicated on i.MX6SX (armv7), which has more complex memory
architecture compared to the i.MX23/28 (armv5).
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>