soc: qcom: update return value for minidump add region

If minidump is not enabled, minidump add region api returns
error number, clients can log the error to log buffer, which
flood the log buffer unnecessarily.

So return quietly if minidump support is not enabled.

Change-Id: I9c6428015ca40c5233f80471896bacecd0872bf7
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>