msm: sensor: actuator: NULL pointer protection for step table

In case of HW failure, actuator step table is not created.
Add NULL pointer check before using step table.
In case of returning with errors, free the variable memory.
This change also removes unused variables.

Change-Id: I09852ea97b95cf256244b89a2e64156f1b9ac711
Signed-off-by: Kyong Hwa Bae <kbae@codeaurora.org>
Signed-off-by: Xu Han <hanxu@codeaurora.org>