qemu: Unify USB controllers across Arm architectures

qemu: Unify USB controllers across Arm architectures

Currently we differentiate between 64-bit and 32-bit
architectures, which doesn't seem very reasonable
considering that the same machine types are available
in both cases. Remove this inconsistency.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>