mtd: rawnand: brcmnand: Use devm_platform_ioremap_resource_byname()

Convert platform_get_resource_byname() + devm_ioremap_resource() to a
single call to devm_platform_ioremap_resource_byname(), as this is
exactly what this function does.

Signed-off-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230802013500.1030853-1-lizetao1@huawei.com