PCI: aardvark: Set PIO_ADDR_LS correctly in advk_pcie_rd_conf()

When setting the PIO_ADDR_LS register during a configuration read, we
were properly passing the device number, function number and register
number, but not the bus number, causing issues when reading the
configuration of PCIe devices.

Fixes: 8c39d710 ("PCI: aardvark: Add Aardvark PCI host controller driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Victor Gu <xigu@marvell.com>
Reviewed-by: Wilson Ding <dingwei@marvell.com>
Reviewed-by: Nadav Haklai <nadavh@marvell.com>
[Thomas: tweak commit log.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>