video: fbdev: uvesafb: Remove impossible code path in uvesafb_init_info

Because uvesafb_vbe_init will fail when get zero avaiable modes,
and we have checked the return value of uvesafb_vbe_init_mode,
so it is impossible to pass NULL as mode into uvesafb_init_info.

[ This patch fix warning report by fengguang.wu@intel.com
  "drivers/video/fbdev/uvesafb.c:1509 uvesafb_init_info()
   error: we previously assumed 'mode' could be null" ]

Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>