drm: zynqmp_dp: Use devm_platform_ioremap_resource_byname()

platform_get_resource_byname() and devm_ioremap_resource() can be
replaced by devm_platform_ioremap_resource_byname(), which can
simplify the code logic a bit, No functional change here.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240828084929.2527228-1-ruanjinjie@huawei.com