Makefile: Add support of CONFIG_SPL_FSL_PBL

Objective of this target to have concatenate binary having
 - SPL binary in PBL command format
 - U-boot binary

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
2 files changed