cnss2: Add extra handlings for RDDM event

There's a change in MHI driver that it will send RDDM event to
CNSS2 directly without sending SYS ERROR event. Hence, add extra
handlings for RDDM event which was done in SYS ERROR handler.

CRs-Fixed: 2483171
Change-Id: Iaf91f38f90bb3ac0b43e1aa152717d48f2d29148
Signed-off-by: Yuanyuan Liu <yuanliu@codeaurora.org>