Whenever ywrap scrolling is selected together with 180 degree screen
rotation, 2.6.15-rc6 and earlier versions are broken.  fb_pan_display()
expects non-negative yoffsets, but ud_update_start() calls it with
yoffsets down to -(yres - font height).  This patch transforms yoffset
to the correct range 0 ...  vyres-1.

Some obviously unneeded parentheses are removed, too.

Verified with cyblafb, should be applied before 2.6.15-final because it
does fix the framebuffer rotation code introduced early in the 2.6.15
release cycle.
Signed-off-by: Knut Petersen <Knut_Petersen@t-online.de>
Acked-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>