vhost_user: implement From instead of Into
vhost_user: implement From instead of Into

Implementing From<...> provides the equivalent Into<..> automatically,
so this form is preferred.

Fixes the clippy from_over_into warning:

https://rust-lang.github.io/rust-clippy/master/index.html#from_over_into

Signed-off-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

rust-vmm/vhost