linux-yocto-rt/4.19: update to -rt16

linux-yocto-rt/4.19: update to -rt16

Integrating the latest 4.19-rt to the preempt-rt branches, the -rt
release announcements summarize the changes:

    Changes since v4.19.25-rt15:

      - The "preserve task state" change in cpu_chill() in the previous
        release is responsible for missing a wake up. Reported by Mike
        Galbraith.

      - The x86-32 lazy preempt code was broken. Reported by Andri Yngvason.

    Changes since v4.19.23-rt13:

      - Use the specified preempt mask in should_resched() on x86.  Otherwise
        a scheduling opportunity of non RT tasks could be missed.

      - Preserve the task state in cpu_chill()

      - Add two more cases to consider before warning about pending
        softirqs.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>