lib: devres: Simplify API devm_iounmap() implementation

Simplify devm_iounmap() implementation by dedicated API devres_release()
compared with current solution, namely, devres_destroy() + iounmap()
devres_release() has the following advantages:

- it is simpler if devm_iounmap()'s parameter @addr is valid, namely
@addr was ever returned by one of devm_ioremap() variants.

- it can avoid unnecessary iounmap(@addr) if @addr is not valid.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240918-fix_lib_devres-v1-1-e696ab5486e6@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>