mtd:fix the bad format in the mtdcore.c

Remove the spare spaces in the head of the lines.
Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>