mhi: dev: satellite: serialize removes for parallel crashes

If multiple remove calls are made, eg. if external device
and any of the internal satellite subsystems go down around the
same time, serialize them using a mutex to ensure walking lists
and other processing is done only once.

CRs-Fixed: 2428157
Change-Id: I58505049fa9eef7666b7c80b04b748a3da58709b
Acked-by: Bhaumik Vasav Bhatt <bbhatt@qti.qualcomm.com>
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>