kmod_module: do not find more than the first command

kmod_module: do not find more than the first command

modprobe from module-init-tools does not use more than one
install/remove command, it just stops on the first one. Test
modprobe.conf:

install bla echo "this is a message"
install bla echo "this is a message"

$ modprobe bla
this is a message
$

Install and remove commands are already a legacy thing we need to carry,
but let's not extend it so people do not start doing crazy things.

With this patch we are breaking on the first element we find in the
configuration. May be we can add a warning later when parsing the config
that install commands are duplicated.