mtd: ssfdc: Fix indentation in ssfdcr_add_mtd()

Replace eight space characters by one tab.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/4045abdd-fb88-4c1f-a947-cdb3d4e59aa6@web.de