sctp_chunks should be put on a diet.  This is some of the low hanging
fruit that we can strip out.  Changes all the __s8/__u8 flags to
bitfields.  Saves 12 bytes per chunk.
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NVlad Yasevich <vladislav.yasevich@hp.com>