staging: unisys: refactor GUEST_DEVICES

Remove the typedef from GUEST_DEVICES and switch to struct
guest_devices. Fix CamelCase names and update all references to renamed
members.

VideoChannel => video_channel
KeyboardChannel => keyboard_channel
NetworkChannel => network_channel
StorageChannel => storage_channel
ConsoleChannel => console_channel
PartitionIndex => partition_index
Pad => pad

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>