fb: update cdev map_base ...

Calling fb_activate_var potentially changes the framebuffer address,
so we have to update the fb0 cdev afterwards.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add the feature to change the video mode at runtime ...

This patch add the possibility to change the video mode at barebox's runtime
if the graphics driver in use supports it.

Signed-off-by: <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Fix default framebuffer 'enable' set ...

To setup the default 'enable' setting the "dev_set_param(dev, "enable", "0");"
does not work as expected. After the call the parameter is still "<NULL>".
This is due to any change of the setting is rejected, if the same setting
is already active.
This patch also let the default setting be successfull, but only calls the
graphics backend if a change happens.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fb: set id for framebuffer device correctly ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fb: add a usage counter to prevent double enable/disable ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

rework device parameters ...

Change device parameters so that the memory management is in generic
code. This also removes the need of storing statically initialized
parameters as they are stored in a struct list_head for each device.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add framebuffer support ...

This patch adds framebuffer support and a driver for i.MX[12]
framebuffer devices.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>