lib: crc64: fix kernel-doc warning

lib: crc64: fix kernel-doc warning

Fix W=1 kernel build warning:

  lib/crc64.c:40: warning:
   bad line:         or the previous crc64 value if computing incrementally.

Link: https://lkml.kernel.org/r/20210601135851.15444-1-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Coly Li <colyli@suse.de>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>