MLK-22768 video: fbdev: mxc_ipuv3_fb: Handle enabled fg properly when set-par happens...

MLK-22768 video: fbdev: mxc_ipuv3_fb: Handle enabled fg properly when set-par happens on bg

When we do set-par for background framebuffer without on-the-fly
flag being set, we should also unset the enabled overlay framebuffer's
on-the-fly flag, otherwise the overlay framebuffer cannot be enabled
again properly because a full mode set procedure is needed for overlay
framebuffer as it experiences a period of time when background
framebuffer stops fetching frames.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
(cherry picked from commit fad9437d99ae234f1c66087d47ad8a547f5f1142)