Bluetooth: HCI: Fix allow Zephyr VS HCI commands in host-only build

Fix unable to select the Zephyr Vendor-Specific HCI commands support in
host-only build. Set VS HCI support as default on if it is known that
the controller supports it. Otherwise set it to off, this means that
VS HCI support will be default off in host-only builds.

Fixes: #21996

Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>