KVM: arm64: nvhe: Add intermediates to 'targets' instead of extra-y

These are generated on demand. Adding them to 'targets' is enough.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220613092026.1705630-2-masahiroy@kernel.org