MIPS: SMP: Allow boot_secondary SMP op to return errors

MIPS: SMP: Allow boot_secondary SMP op to return errors

Allow the boot_secondary SMP op to return an error to __cpu_up(), which
will in turn return it to its caller.

This will allow SMP implementations to return errors quickly in cases
they they know have failed, rather than relying upon __cpu_up()
eventually timing out waiting for the cpu_running completion.

Signed-off-by: Paul Burton <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/17014/
Signed-off-by: Ralf Baechle <[email protected]>