hwspinlock: stm32: convert to devm_platform_ioremap_resource

Use devm_platform_ioremap_resource() to simplify code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Link: https://lore.kernel.org/r/20191228191541.26999-1-tiny.windzz@gmail.com


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