PCI: rcar: Add support for R-Car H3 to pcie-rcar

Add the "renesas,pcie-r8a7795" property for the R-Car H3 device to the
pcie-rcar driver.

Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Harunobu Kurokawa <harunobu.kurokawa.dn@renesas.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>