carl9170: allow kconfig options in autogen.sh's parameters

carl9170: allow kconfig options in autogen.sh's parameters

kconf supports several interesting options:
 --allnoconfig    New config where all options are answered with no
 --allyesconfig   New config where all options are answered with yes
 --alldefconfig   New config with all symbols set to default
 --randconfig     New config with random answer to all options

to build the default firmware image, it is enough to run:
./autogen.sh --alldefconfig

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>