esoc: mdm: Reset esoc only if the system is resetting

We now cold reset the esoc only if the system is resetting.
Earlier we would reset it in the shut down flow as well.
This was causing the mdm to get powered on again since it
had already been shut down at this point.

Change-Id: I3041f3e4983f8c29212cd48a52fec3b8d2c90f93
Signed-off-by: Ameya Thakur <ameyat@codeaurora.org>