msm: ipa: Protect the access to LAN CONS client notification call-back

When a packet is received on LAN_CONS pipe, IPA driver will notify the
source EP driver with a packet received event notification.
This is done via calling the source EP notification call-back.
There could be a race condition with calling the call-back and nullifing
it by other execution thread. For example, on EP disconnect. Spin lock
is being used to protect this access.

CRs-Fixed: 857971
Change-Id: I7b142c791e11507c18a5b346bbf22623ac57cbad
Signed-off-by: Ghanim Fodi <gfodi@codeaurora.org>