ltq-vdsl-app: enable G.993.5 XTSE bit by default

ltq-vdsl-app: enable G.993.5 XTSE bit by default

According to ITU-T G.997.1 Amendment 2 (04/2013) section 2.1, bit 3 of
XTSE octet 8 either allow or denies the initialization of G.993.5.

Even if the current redistributable xDSL firmware doesn't include
G.993.5 vectoring support, enable this bit by default to allow people to
get their G.993.5 line working using a custom xDSL firmware.

Signed-off-by: Mathias Kresin <openwrt@kresin.me>
SVN-Revision: 48053