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

LU-4975 ofd: add comments for ofd_grant.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_grant.c file.
- Add function comments blocks to all functions in the ofd_grant.c
  file

Signed-off-by: Johann Lombardi <johann.lombardi@intel.com>
Change-Id: I51400354ae51a2d989f136c7dad389d88193a2e5
Reviewed-on: http://review.whamcloud.com/10586
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Richard Henwood <richard.henwood@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>