Bootrom will put cpus into WFE state when boot cpu release cpus, so
target cpu cannot correctly go to spin state.
Add 'sev' to wakeup non-boot cpu that hold on bootrom space, let target
cpu can fall into u-boot spin table.
Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>