docs: automarkup.py: Add cross-reference for parametrized C macros

Sphinx 3 added support for declaring C macros with parameters using the
:c:macro role.

To support automarkup for both functions and parametrized macros using
the same regex (words ending in ()), try to cross-reference to both, and
only fall back to regular text if neither exist.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@protonmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>