pci: sh7751: Convert to DM and DT probing

Convert the SH7751 PCI driver to DM and add DT probing.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Bin Meng <bmeng.cn@gmail.com>