msm: pil: Unregister modem notifer on failure to create kobj

Correct functionality to unregister the modem notifier if creating
a kobject for the audio voice service fails.

Change-Id: I51ddd33bcc6b69172cc006e599ab7182d39e4dbd
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>