kvm tools: Rename --host-ip-addr to --host-ip

This patch makes the network options more consistent.

We are having:

   --host-ip
   --host-mac
   --guest-ip
   --guest-mac

now.

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>