mtd: inftl.h: fix spacing errors

Replaced some spaces with tabs to fit CodingStyle guidelines
Signed-off-by: NBrian Norris <norris@broadcom.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>