libxl: Fix broken build attach/detach controller device
libxl: Fix broken build attach/detach controller device

Commit id '44304c6eb' added the API libxlDomainAttachControllerDevice
inside a conditional LIBXL_HAVE_PVUSB, but called that function outside
the conditional in libxlDomainAttachDeviceLive.

Similarly, the API libxlDomainDetachControllerDevice was added inside a
conditional LIBXL_HAVE_PVUSB, but called outside the conditional in
libxlDomainDetachDeviceLive.

This patch adds the conditional LIBXL_HAVE_PVUSB around those two calls
from within the switch.

nertpinx/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,libvirt/libvirt,eskultety/libvirt,taget/libvirt,datto/libvirt,andreabolognani/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,zippy2/libvirt,crobinso/libvirt,taget/libvirt,jfehlig/libvirt,taget/libvirt,datto/libvirt,andreabolognani/libvirt,jardasgit/libvirt,olafhering/libvirt,jardasgit/libvirt,taget/libvirt,eskultety/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,crobinso/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,olafhering/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,VenkatDatta/libvirt,nertpinx/libvirt,libvirt/libvirt,crobinso/libvirt,andreabolognani/libvirt,datto/libvirt,jardasgit/libvirt,zippy2/libvirt,zippy2/libvirt,VenkatDatta/libvirt,zippy2/libvirt,olafhering/libvirt,datto/libvirt,crobinso/libvirt,jfehlig/libvirt,jardasgit/libvirt,taget/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt,datto/libvirt,olafhering/libvirt,libvirt/libvirt,eskultety/libvirt,libvirt/libvirt,eskultety/libvirt,nertpinx/libvirt,eskultety/libvirt,nertpinx/libvirt