soc: qcom: hab: replace kref_get with kref_get_unless_zero

If refcount was 0 before increment, it maybe has a race condition that
this kref is freeing by some other thread right now. In this case we should
not increments refcount, so replace with kref_get_unless_zero.

Change-Id: Ic15eaefc111770a966094d05b19eca2a04d52fc2
Signed-off-by: Yao Jiang <yaojia@codeaurora.org>