udeb: Really add virtio_input to virtio-modules (not input-modules)

kernel-wedge is sensitive to the difference between '-' and '_' so
adding 'virtio-input ?' to input-modules had no effect.

If we really added virtio_input to input-modules then we would end up
with virtio and virtio_ring duplicated.  Instead, add it to
virtio-modules like all the other virtio drivers.

debian/changelog

@@ -30,6 +30,7 @@ linux (4.4.1-1) UNRELEASED; urgency=medium
     - nic-pcmcia-modules: Remove Arcnet drivers
   * udeb: Move most USB wireless drivers from nic-usb-modules to
     nic-wireless-modules
+  * udeb: Really add virtio_input to virtio-modules (not input-modules)
 
   [ Roger Shimizu ]
   * Enable TTY_PRINTK as module (Closes: #814540).

debian/installer/modules/input-modules

@@ -35,6 +35,5 @@ wacom -
 # Miscellaneous input drivers
 synaptics_usb ?
 wistron_btns ?
-virtio-input ?
 gpio_keys ?
 soc_button_array ?

debian/installer/modules/virtio-modules

@@ -2,6 +2,7 @@ virtio_net
 virtio_blk
 virtio_balloon
 virtio_scsi
+virtio_input
 
 # Some architectures do not have PCI bus
 virtio_pci ?