Rename hw/nestvirt support from -vmx to -hwv.

Created by: garloff

vmx is actually an intel specific name; it's called svm on AMD. (Good catch from Mathias, thanks!)

So chose a name that is neutral -- not only for x86-64, but even for arm and others: hwv is short for hardware virtualization.

Signed-off-by: Kurt Garloff kurt@garloff.de