KVM: arm64: Enforce dependency on an ARMv8.4-aware toolchain

KVM: arm64: Enforce dependency on an ARMv8.4-aware toolchain

With the NV support of TLBI-range operations, KVM makes use of
instructions that are only supported by binutils versions >= 2.30.

This breaks the build for very old toolchains.

Make KVM support conditional on having ARMv8.4 support in the
assembler, side-stepping the issue.

Fixes: 5d476ca57d7d ("KVM: arm64: nv: Add handling of range-based TLBI operations")
Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Suggested-by: Arnd Bergmann <arnd@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240807115144.3237260-1-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>