Remove obsolete udev_root references

This was removed in 6ada823a9a

man/udev.7

@@ -515,11 +515,6 @@ The current name of the device\&. If not changed by a rule, it is the name of th
 A space\-separated list of the current symlinks\&. The value is only set during a remove event or if an earlier rule assigned a value\&.
 .RE
 .PP
-\fB$root\fR, \fB%r\fR
-.RS 4
-The udev_root value\&.
-.RE
-.PP
 \fB$sys\fR, \fB%S\fR
 .RS 4
 The sysfs mount point\&.

man/udev.xml

@@ -702,13 +702,6 @@
           </listitem>
         </varlistentry>
 
-        <varlistentry>
-          <term><option>$root</option>, <option>%r</option></term>
-          <listitem>
-            <para>The udev_root value.</para>
-          </listitem>
-        </varlistentry>
-
         <varlistentry>
           <term><option>$sys</option>, <option>%S</option></term>
           <listitem>

test/udev-test.pl

@@ -886,14 +886,6 @@ EOF
                 exp_name        => "sda-part-1",
                 rules           => <<EOF
 SUBSYSTEMS=="scsi", KERNEL=="sda1", SYMLINK+="%P-part-1"
-EOF
-        },
-        {
-                desc            => "udev_root substitution",
-                devpath         => "/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda1",
-                exp_name        => "start-/dev-end",
-                rules           => <<EOF
-SUBSYSTEMS=="scsi", KERNEL=="sda1", SYMLINK+="start-%r-end"
 EOF
         },
         {