hwspinlock: Simplify Kconfig

Every hwspinlock driver is expected to depend on the
hwspinlock core, so it's possible to simplify the
Kconfig, factoring out the HWSPINLOCK dependency.

Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Link: https://lore.kernel.org/r/20200414220943.6203-1-ezequiel@collabora.com


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>