slim_ngd: notify slaves in some MDM restart scenarios

If MDM restarts when it had active framer, bus may lose sync.
Send device-down notification if that happens, and corresponding
reset-device and device-up notifications to slaves so that they
can act to restore their devices' communication over slimbus

CRs-Fixed: 612775
Change-Id: I83f22b9bcf18912c7c9507ea099691ed71d86a9f
Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>