PCI: Add support for ACPI _RST reset method

_RST is a standard ACPI method that performs a function level reset of a
device (ACPI v6.3, sec 7.3.25).

Add pci_dev_acpi_reset() to probe for _RST method and execute if present.
The default priority of this reset is set to below device-specific and
above hardware resets.

Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20210817180500.1253-9-ameynarkhede03@gmail.com
Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6da5f6d..4d98281 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5126,6 +5126,7 @@ static void pci_dev_restore(struct pci_dev *dev)
 static const struct pci_reset_fn_method pci_reset_fn_methods[] = {
 	{ },
 	{ pci_dev_specific_reset, .name = "device_specific" },
+	{ pci_dev_acpi_reset, .name = "acpi" },
 	{ pcie_reset_flr, .name = "flr" },
 	{ pci_af_flr, .name = "af_flr" },
 	{ pci_pm_reset, .name = "pm" },