soc: qcom: glink: Fix memory leak from G-Link SSR notification message

The G-Link SSR driver never frees the space allocated for the SSR
notification message.

Free the space after the message has been sent and the response
received.

Change-Id: I982f9d175a2083c5a39dc5c7f8a767cfab3d5dcf
Signed-off-by: Steven Cahail <scahail@codeaurora.org>