Hardware supports PCIe Hot Reset via PCIE_CTRL_OFF register. Use it for
implementing PCI_BRIDGE_CTL_BUS_RESET bit of PCI_BRIDGE_CONTROL register on
emulated bridge.

With this change the function pci_reset_secondary_bus() starts working and
can reset connected PCIe card.

Link: https://lore.kernel.org/r/20211125124605.25915-13-pali@kernel.org
Fixes: 1f08673e ("PCI: mvebu: Convert to PCI emulated bridge config space")
Signed-off-by: NPali Rohár <pali@kernel.org>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>