msm: ipa: generic uC loaded event notifier support

Existing uC loaded event notifier allows only a single client per uC
hardware feature to register for the notification. With uC offload
feature shared among multiple networking hardware, we need to allow
multiple offload clients to register for the uC loaded event. Since
uC loaded event is generic in nature, add a generic uC loaded event
notifier mechanism usable by all clients.

CRs-Fixed: 2304918, 2337876
Change-Id: Iadaa9382e15f35103ea5ee896901ccf81f086e55
Signed-off-by: Jinesh K. Jayakumar <jineshk@codeaurora.org>