Remove most doxygen file-level commands, copyrights, and authors

Remove the \file directive, as it is always superfluous  because the
current file is implicit [1]:

> If the file name is omitted (i.e. the line after \file is left blank)
> then the documentation block that contains the \file command will belong
> to the file it is located in.

Author names and e-mails are not relevant for us: it can always be
inferred from git blame, and is often outdated.

Eurecom code has been contributed and was under OAI PL v1.0/v1.1.

For the cpack package contact: put generic email address that is
independent of an individual and that will remain reachable.

[1] https://www.doxygen.nl/manual/commands.html#cmdfile

executables/softmodem-common.c

@@ -19,15 +19,8 @@
  *      contact@openairinterface.org
  */
 
-/*! \file softmodem-common.c
+/*!
  * \brief common code for 5G and LTE softmodem main xNB and UEs source (nr-softmodem.c, lte-softmodem.c...)
- * \author Nokia BellLabs France, francois Taburet
- * \date 2020
- * \version 0.1
- * \company Nokia BellLabs France
- * \email: francois.taburet@nokia-bell-labs.com
- * \note
- * \warning
  */
 #include <time.h>
 #include <dlfcn.h>