x86: Call early_board_init when warm booting

x86: Call early_board_init when warm booting

early_board_init has been skipped to avoid SDRAM corruption in the case
that a fully relocatable image has been loaded into SDRAM and is being
executed from SDRAM. x86 is being aligned with other architectures (ARM
and PPC in particlar) and will be using Cache-As-RAM to run a C
environment from Flash (or SRAM if you have some). early_board_init may
be needed to assist in the setup of Cache-As-RAM and the early C
environment