Minidump: Add update region support for minidump regions

Add support to update client's entry physical/virtual addresses,
which is useful for DLKM, dynamic address changing clients.

Currently, msm_minidump_add_region() returns 0 on success, instead
of that, return 'region number' of the entry in the minidump table.

So clients who wants to update their address in future, needs to
book keep their entry in minidump table.

Change-Id: I03abbbd87bf6d2e11cf637525412d352772821cf
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
[neeraju@codeaurora: Add mdt_remove_lock to serialize with removal]
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>