Set the resource type when we reserve VGA-related I/O port resources.
The resource code doesn't actually look at the type, so it inserts
resources without a type in the tree correctly even without this change.
But if we ever print a resource without a type, it looks like this:
vga+ [??? 0x000003c0-0x000003df flags 0x0]
Setting the type means it will be printed correctly as: