fbdev: mxsfb: use framebuffer_alloc in the correct way
framebuffer_alloc allocated the fb_info struct plus the extra
par and set fb_info->par pointer equal to this extra par. We
can refer the mxcfb_info from fb_info->par
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com> Reviewed-by: Stefan Agner <stefan@agner.ch> Tested-by: Stefan Agner <stefan@agner.ch> Cc: Shawn Guo <shawnguo@kernel.org> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>