phy: renesas: r8a779f0-ether-serdes: Convert to devm_platform_ioremap_resource()

Use devm_platform_ioremap_resource() to simplify code.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Link: https://lore.kernel.org/r/20230705090126.26854-3-frank.li@vivo.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>