arm64: write to daifclr instead of daif on irq restore

arm64: write to daifclr instead of daif on irq restore

On Denver cores, 'msr daif' falls back to a longflow. If we know
we're only changing the status of the 'i' bit (as we do with
'msr daifclr #2'), we can inline a simpler longflow.

Change-Id: Ief0768c55ad8612ed299765a81272436d780b5db
Signed-off-by: Rich Wiley <rwiley@nvidia.com>
Reviewed-on: http://git-master/r/1140649
(cherry picked from commit c762b187e24953ffec264cffc82c31e3cd0e333e)
Reviewed-on: http://git-master/r/1253016
GVS: Gerrit_Virtual_Submit
Reviewed-by: Rohit Khanna <rokhanna@nvidia.com>