mtd: nand: fsmc: remove CONFIG_OF conditional

Since commit 4404d7d8

 ("mtd: nand: fsmc: remove stale non-DT probe
path"), the fsmc NAND driver only supports Device Tree probing, and
therefore has a "depends on OF" in its Kconfig option.

Due to this the #ifdef CONFIG_OF ... #endif condition in the driver code
is no longer necessary.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>