powerpc/mpc85xx: Remove SPI and NAND partition from bsc9131rdb.dtsi

* Run "mtdparts default" on u-boot to create dynamic partitions
 * Or use dynamic mtd partition with the help of bootargs in u-boot
   Append bootargs with:
    "mtdparts=ff800000.flash:1m(nand_uboot),512K(nand_dtb),8m(nand_kernel),-(fs);\
     spiff707000.0:1m(spi_uboot),4m(spi_kernel),512k(spi_dtb),-(fs)'"

Signed-off-by: Ashish Kumar <Ashish.Kumar@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>