tc2: android: remove duplicate user networking params

user networking mode is enabled by default, so in case of android
booting, user networking paramaters are duplicated as currently they are
also appended to DISTRO_MODEL_PARAMS.

As user networking parameters are part of DISTRO_MODEL_PARAMS, they are
passed to model even if explicit tap interface is provided which enables
user networking mode instead of tap interface.

so remove user networking parameters from DISTRO_MODEL_PARAMS in case
of android booting, let only default user netwroking mode take care of
networking when there is no explicit -t or -n arguments.

Signed-off-by: Jagdish Gediya <jagdish.gediya@arm.com>