hwspinlock: Add devm_xxx() APIs to register/unregister one hwlock controller

This patch introduces devm_hwspin_lock_register() and devm_hwspin_lock_unregister()
interfaces to help to register or unregister one hardware spinlock controller, that
will help to simplify the cleanup code for hwspinlock drivers.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>