powerpc/mpc85xx: new SPL support for IFC NAND

Linker script is not able find start.o binary. So add its absolute path in
u-boot-spl.lds. This change is similar to u-boot-nand.lds

common/Makefile: Avoid compiling unnecssary files

fsl_ifc_spl.c : It is is responsible for reading u-boot binary from
NAND flash and copying into DDR. It also transfer control from NAND SPL
to u-boot image present in DDR.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>