mtd: onenand: Trivial cleanup in samsung.h

commit 93115b7f ("mtd: onenand/samsung: make regs-onenand.h file local")
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: Brian Norris <computersforpeace@gmail.com>