hwspinlock: sprd: Use devm_hwspin_lock_register() to register hwlock controller

Use devm_hwspin_lock_register() to register the hwlock controller instead of
unregistering the hwlock controller explicitly when removing the device.

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