[PATCH] fb_videomode_to_var: reset virtual screen parameters

fb_videomode_to_var(): reset the virtual screen parameters when converting
from an fb_videomode to an fb_var_screeninfo.

Without this the old virtual screen parameters are kept.  Hence you cannot
switch to a video mode with a lower resolution on frame buffer devices that
don't support virtual screens and panning, as values are not supposed to be
rounded down when they don't fit.

I also reordered the assignments to match the order of the individual members.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Cc: James Simmons <jsimmons@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>