Remove old comment, we already do 802.1q tagging.

Phabric:	D797
Reviewed by:	kevlo
Approved by:	kevlo
Sponsored by:	QNAP Systems Inc.
r258695 introduces a sanity check for makefs in order to verify that
the minimum image size specified is always less than the maximum
image size. If makefs(1) is invoked specifying minimum image size,
but not maximum one, the program exits with an error. Example:

# sudo -E makefs -M 538968064 -B be /home/davide/disk.img $DESTDIR
makefs: `/home/davide/tftproot/mips' minsize of 538968064 rounded up
to ffs bsize of 8192 exceeds maxsize 0.  Lower bsize, or round the
minimum and maximum sizes to bsize.

Assert then that minsize < maxsize iff maxsize is specified.
This change allows me to build MIPS images using makefs(1) and following
what specified in the wiki again.

Reviewed by:	jmallett, ngie