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: 4ae0b32e ("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