fbdev: uvesafb: Simplify uvesafb_remove()

When the remove() function is called, we know that the probe() function has
successfully been executed. So 'info' is known to be not NULL.

Simplify the code accordingly.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Helge Deller <deller@gmx.de>