fbdev: fix obvious bug in show_pan()

show_pan will display the value of the xoffset twice, instead of the xoffset
and yoffset.  Fix.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>