LU-4975 ofd: add comments for ofd_capa.c functions

LU-4975 ofd: add comments for ofd_capa.c functions

- Fix up GPL header block to reference proper GPLv2 license URL.
- Remove mention of contacting Sun.
- Add introductionary comment block for the ofd_capa.c file.
- Add function comments blocks to all functions in the ofd_capa.c
  file
- Remove cfs_ prefix from list_head functions

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: I7210ed43c7d089e86d978e6033c3f4659bc41f52
Reviewed-on: http://review.whamcloud.com/10606
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Richard Henwood <richard.henwood@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>