We handle ID_AA64MMFR4_EL1.E2H0 being 0 as NV1 being present.
However, this is only true if FEAT_NV is implemented.

Add the required check to has_nv1(), avoiding spuriously advertising
NV1 on HW that doesn't have NV at all.

Fixes: da9af507 ("arm64: cpufeature: Detect HCR_EL2.NV1 being RES0")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240212144736.1933112-3-maz@kernel.orgSigned-off-by: Oliver Upton <oliver.upton@linux.dev>