core: remove extra thread_create_arg() function

core/include/thread.h

core/kernel_init.c

core/thread.c

cpu/x86/x86_hwtimer.c

drivers/cc110x/cc1100_phy.c

examples/ccn-lite-client/main.c

examples/ccn-lite-relay/main.c

examples/default/main.c

examples/ipc_pingpong/main.c

examples/riot_and_cpp/main.cpp

examples/rpl_udp/demo.h

examples/rpl_udp/helper.c

examples/rpl_udp/rpl.c

examples/rpl_udp/udp.c

sys/auto_init/auto_init.c

sys/chardev_thread.c

sys/include/chardev_thread.h

sys/net/include/etx_beaconing.h

sys/net/network_layer/sixlowpan/ip.c

sys/net/network_layer/sixlowpan/ip.h