x86: Use microcode update from device tree for all processors

Built without a ROM image with FSP (u-boot.rom), the U-Boot loader applies
the microcode update data block encoded in Device Tree to the bootstrap
processor but not passed to the other CPUs when multiprocessing is enabled.

If the bootstrap processor successfully performs a microcode update
from Device Tree, use the same data block for the other processors.

Signed-off-by: Ivan Gorinov <ivan.gorinov@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: fixed build errors on edison and qemu-x86]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>