remoteproc/mediatek: acknowledge watchdog IRQ after handled

Acknowledges watchdog IRQ after handled or kernel keeps receiving the
interrupt.

Fixes: fd0b6c1f ("remoteproc/mediatek: Add support for mt8192 SCP")
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20210127082046.3735157-1-tzungbi@google.com


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>