drm/mxsfb/lcdif: move iteration-specific variables declaration inside loop in lcdif_a...

drm/mxsfb/lcdif: move iteration-specific variables declaration inside loop in lcdif_attach_bridge

The bridge and ret variables are per-iteration variables, whose values
don't have to be carried to the next iteration or be used after the loop
end. Move their declaration inside the loop scope as a cleanup and to make
code clearer.

Reviewed-by: Liu Ying <victor.liu@nxp.com>
Link: https://patch.msgid.link/20260407-drm-lcdif-dbanc-v4-4-247a16e61ef9@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>