soc: qcom: rpm-smd-debug: initialize variables and check for return value

Initialize few variables and check return value of sscanf.
use 'goto' to exit without sending rpm send message request
in case of sscanf failure.

Change-Id: I86f723b4dbbca30b80a33de8b2c28116da8730dd
Signed-off-by: Naresh Malladi <namall@codeaurora.org>