docs: ABI: sysfs-bus-event_source-devices-vpa-pmu: Fix htmldocs errors

Fix errors during `make htmldocs`, eg:

  Documentation/ABI/testing/sysfs-bus-event_source-devices-vpa-pmu:2: ERROR: Unexpected indentation.

Fixes: 4ae0b32 ("docs: ABI: sysfs-bus-event_source-devices-vpa-pmu: Document sysfs event format entries for vpa_pmu")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/all/20241120171302.2053439c@canb.auug.org.au/
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241124103006.2236073-1-mpe@ellerman.id.au

Documentation/ABI/testing/sysfs-bus-event_source-devices-vpa-pmu

@@ -8,17 +8,18 @@ Description:    Read-only. Attribute group to describe the magic bits
                 Each attribute under this group defines a bit range of the
                 perf_event_attr.config. Supported attribute are listed
                 below::
-			event = "config:0-31" - event ID
 
-		For example::
+                  event = "config:0-31" - event ID
 
-		  l1_to_l2_lat = "event=0x1"
+                For example::
+
+                  l1_to_l2_lat = "event=0x1"
 
 What:           /sys/bus/event_source/devices/vpa_pmu/events
 Date:           November 2024
 Contact:        Linux on PowerPC Developer List <linuxppc-dev@lists.ozlabs.org>
-Description:	Read-only. Attribute group to describe performance monitoring
+Description:    Read-only. Attribute group to describe performance monitoring
                 events for the Virtual Processor Area events. Each attribute
-		in this group describes a single performance monitoring event
-		supported by vpa_pmu. The name of the file is the name of
-		the event (See ABI/testing/sysfs-bus-event_source-devices-events).
+                in this group describes a single performance monitoring event
+                supported by vpa_pmu. The name of the file is the name of
+                the event (See ABI/testing/sysfs-bus-event_source-devices-events).