drivers: provide devm_platform_ioremap_resource_byname()

Provide a variant of devm_platform_ioremap_resource() that allows to
lookup resources from platform devices by name rather than by index.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20191022084318.22256-7-brgl@bgdev.pl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>