usr.sbin/makefs: Sync with sys/vfs/hammer2

usr.sbin/makefs: Sync with sys/vfs/hammer2

Sync with following sys/vfs/hammer2 commits.

$ git log --pretty="%h %s" 6966bebf98ca11fee72e5ba9849224a5049211dd.. -- sys/vfs/hammer2/
23d820f091 sys/vfs/hammer2: Use howmany() to calculate bulkfree bmap size
e12df3bcd3 sys/vfs/hammer2: Fix comment on bmradix in freemap
8d92096877 sys/vfs/hammer2: Remove obsolete comments in freemap
f517f709f2 sys/vfs/hammer2: Remove redundant NULL chain test in bulkfree
c4cc6dbe36 sys/vfs/hammer2: Remove obsolete code/comment in freemap
a4cea70ee4 sys/vfs/hammer2: Fix 53b767003a to use plural
53b767003a sys/vfs/hammer2: Fix multiple "radii" -> "radix"