hwspinlock: ignore disabled device

Do not wait for hwspinlock device registration if it is not available
for use.

Acked-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>