misc: ibmasm: Return error on error path

If ibmasm_event_buffer_init() or ibmasm_heartbeat_init() fails,
then ibmasm_init_one() release all resources and return 0 on error path.

The patch adds corresponding error for fails.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>