pinctrl: renesas: rzn1: Fix possible null-ptr-deref in sh_pfc_map_resources()

pinctrl: renesas: rzn1: Fix possible null-ptr-deref in sh_pfc_map_resources()

It will cause null-ptr-deref when using 'res', if platform_get_resource()
returns NULL, so move using 'res' after devm_ioremap_resource() that
will check it to avoid null-ptr-deref.
And use devm_platform_get_and_ioremap_resource() to simplify code.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20220429082637.1308182-2-yangyingliang@huawei.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>