netif-naming-scheme: disable NAMING_BRIDGE_MULTIFUNCTION_SLOT

This effectively reverts 66425da.

The commit assumes that if the network interface has multifunctions,
then the function fields of the pci devices under the same PCI bridge
device are unique.
But it seems not, at least on some setups. See issue #28929.
Let's revert the change, and always refuse to set slot base naming if
a PCI bridge is detected.

Fixes #28929.

(cherry picked from commit af7417a)

Resolves: RHEL-44630

man/systemd.net-naming-scheme.xml

@@ -499,6 +499,20 @@
 
            <listitem><para>Same as naming scheme <constant>rhel-9.3</constant>.</para></listitem>
         </varlistentry>
+
+        <varlistentry>
+            <term><constant>rhel-9.5</constant></term>
+
+          <listitem><para>Never generate a slot name when a PCI bridge is detected.</para>
+
+          <para>Since version <constant>"rhel-9.0"</constant>, we have generated slot-based names
+          for PCI multifunction devices, because we assumed that it is enough to use function numbers
+          to distinguish between devices. However, name conflict can occur if these devices are not
+          children of the same PCI bridge, e.g. there are multiple PCI bridges in the same slot.
+          </para>
+          </listitem>
+        </varlistentry>
+
       </variablelist>
 
     <para>By default <constant>rhel-9.0</constant> is used.</para>

src/shared/netif-naming-scheme.h

@@ -38,7 +38,8 @@ typedef enum NamingSchemeFlags {
         NAMING_16BIT_INDEX               = 1 << 11, /* Allow full 16-bit for the onboard index */
         NAMING_REPLACE_STRICTLY          = 1 << 12, /* Use udev_replace_ifname() for NAME= rule */
         NAMING_XEN_VIF                   = 1 << 13, /* Generate names for Xen netfront devices */
-        NAMING_BRIDGE_MULTIFUNCTION_SLOT = 1 << 14, /* Use PCI hotplug slot information associated with bridge, but only if PCI device is multifunction */
+        NAMING_BRIDGE_MULTIFUNCTION_SLOT = 1 << 14, /* Use PCI hotplug slot information associated with bridge, but only if PCI device is multifunction.
+                                                     * This is disabled since rhel-9.5, as it seems not to work at least for some setups. See upstream issue #28929. */
         NAMING_DEVICETREE_ALIASES        = 1 << 15, /* Generate names from devicetree aliases */
         NAMING_SR_IOV_R                  = 1 << 17, /* Use "r" suffix for SR-IOV VF representors */
 
@@ -72,6 +73,7 @@ typedef enum NamingSchemeFlags {
         NAMING_RHEL_9_2 = NAMING_RHEL_9_0,
         NAMING_RHEL_9_3 = NAMING_RHEL_9_0 | NAMING_SR_IOV_R,
         NAMING_RHEL_9_4 = NAMING_RHEL_9_3,
+        NAMING_RHEL_9_5 = NAMING_RHEL_9_4 & ~NAMING_BRIDGE_MULTIFUNCTION_SLOT,
 
         EXTRA_NET_NAMING_SCHEMES