ARM: SMP: use a timing out completion for cpu hotplug
    ARM: SMP: use a timing out completion for cpu hotplug

    Rather than open-coding the jiffy-based wait, and polling for the
    secondary CPU to come online, use a completion instead.  This
    removes the need to poll, instead we will be notified when the
    secondary CPU has initialized.

Change-Id: If0cb7c0905fbc22d1b552bc3da05f54f50c5c301
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>