qcom: sysmon: Correct dest_ss comment text for sysmon_send_event

The dest_ss parameter passed in with the sysmon_send_event
function is no longer an enum. Correct the comment text to
reflect its change to a string.

Change-Id: Ie2727827f02a59c085924ce70ca37f4f41fc60e5
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>