xivo-yealink: remove invalid line in M7+M2 config file

Lines starting with a comma are not valid in the M7+M2 configuration
file. At least, the T38 is not updating its configuration when this line
is present.
xivo-yealink: homogenize the common config files

A little bit.
xivo-yealink: remove xivo-yealink-71.0

It supports the T4X phones, which are already supported by the newer
xivo-yealink-72.0 plugin.
xivo-yealink: update firmware for xivo-yealink-70.0
xivo-yealink: update plugins version