hostfs: remove "will unlock" comment

A "will unlock" comment was added to hostfs in the following commit,
along with a spinlock:

Commit e9193059b1b3733695d5b80e667778311695aa73 ("hostfs: fix races in
dentry_name() and inode_name()").

But the spinlock was subsequently removed in the following commit:

Commit ec2447c278ee973d35f38e53ca16ba7f965ae33d ("hostfs: simplify
locking").

Since the comment is no longer applicable, remove it.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>