video: pxa: Cleanup video-pxafb.h header

Commit 293b2da1 ("ARM: pxa: move platform_data definitions")
moved the file to the current location but forgot to remove the pointer
to its previous location. Clean it up.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>