arm64: add spinlock implementation

Provide a simple spinlock implentation for arm64. A value
of 0 is unlocked and a value of 1 is locked.

BUG=chrome-os-partner:31761
BRANCH=None
TEST=Built and ran SMP bringup on ryu.

Change-Id: Ie88a715a6b51cd38a5fdd830583dae528cc49d67
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 14dab94610c96d6b1530c64d661833f8e613101c
Original-Change-Id: I3bf2d80b91112d04442455ff0fa3f16900b7327f
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/216923
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/9040
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
1 file changed