power: qcom-step-chg: Fix the error return path

Fix the error return path in qcom_step_chg_init() to free up the
allocated memory and registered wake source.

Change-Id: I8f93246d27f79a7c759b3afc4a4544d9ffca7a80
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>