doc: fix "WARNING: Error in type declaration." in callback typedefs

Some function *typedefs* confuse the *Sphynx* / *breathe* parser [see
the patch for full details]. Implement a workaround (defining the name
with @typedef), add workaround documentation and file a bug with the
sphinx/breathe developers.

Change-Id: I7f3dba4a53d0cc73e12f02511a5f85526f357b5f
Signed-off-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
8 files changed