scripts: get_abi.pl: improve its parser to better catch up indentation

The original parser for indentation were relying on having
just one description for each "what". However, that's not
the case: there are a number of ABI symbols that got defined
multiple times.

Improve the parser for it to better handle descriptions
if entries are duplicated.

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/eb458bb30be0e5a89192d6057b2e8a7e910dbcb8.1604042072.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>