batman-adv: Use consistent name for mesh interface

batman-adv: Use consistent name for mesh interface

The way how the virtual interface is called inside the batman-adv source
code is not consistent. The genl headers call it meshif and the rest of the
code calls is (mostly) softif.

The genl definitions cannot be touched because they are part of the UAPI.
But the rest of the batman-adv code can be touched to have a consistent
name again.

The bulk of the renaming was done using

  sed -i -e 's/soft\(-\|\_\| \|\)i\([nf]\)/mesh\1i\2/g' \
         -e 's/SOFT\(-\|\_\| \|\)I\([NF]\)/MESH\1I\2/g'

and then it was adjusted slightly when proofreading the changes.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>