mtd: omap2: Cleanup header files

Commit 2203747c

 ("ARM: omap: move platform_data definitions")
moved the files 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>
Acked-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>