[MTD] [NAND] Fix compilation warnings in drivers/mtd/nand/cs553x_nand.c

Below patch fixes the following compilation warnings.
drivers/mtd/nand/cs553x_nand.c:293: warning: unused variable 'mtd_parts'
drivers/mtd/nand/cs553x_nand.c:292: warning: unused variable 'mtd_parts_nb'

Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>