Documentation: coresight: tpdm: Add dummy comment after sysfs list

kernel test robot reported htmldocs warning:

Documentation/trace/coresight/coresight-tpdm.rst:43: WARNING: Document may not end with a transition.

Since there is no more documentation left for TPDM, fix the warning by adding
dummy comment, thus creating the required text transition.

Link: https://lore.kernel.org/linux-doc/[e-mail]/
Fixes: 758d638667d474 ("Documentation: trace: Add documentation for TPDM and TPDA")
Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Bagas Sanjaya <[e-mail]>
Signed-off-by: Suzuki K Poulose <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/trace/coresight/coresight-tpdm.rst

···
     value -  1 or 2.
 
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+
+.. This text is intentionally added to make Sphinx happy.