PCI: Increment PM usage counter when probing reset methods

We can get different results probing reset methods for a device depending
on its power state.  For example, reading the PM control register of a
device in D3cold will always indicate NoSoftRst+ because we get ~0 data
when the config read fails on PCI, preventing us from correctly probing PM
reset support.

Increment the PM usage counter before any probes and use the cleanup __free
facility to automatically drop the usage counter out of scope.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20250422230534.2295291-3-alex.williamson@redhat.com

Author: Alex Williamson

drivers/pci/pci-sysfs.c

@@ -1475,6 +1475,9 @@ static ssize_t reset_method_store(struct device *dev,
 		return count;
 	}
 
+	pm_runtime_get_sync(dev);
+	struct device *pmdev __free(pm_runtime_put) = dev;
+
 	if (sysfs_streq(buf, "default")) {
 		pci_init_reset_methods(pdev);
 		return count;