fs/logfs/readwrite.c: kernel-doc warning fixes

s/-/:/ and fix variable names.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Joern Engel <joern@logfs.org>
Cc: Prasad Joshi <prasadjoshi.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>