Fix spelling error in fs_getcrypt man page

priviledges -> privileges

Change-Id: I2026b8df83f3620565d8d8c522209fe354498418
Reviewed-on: http://gerrit.openafs.org/9984
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>