target/arm: Correct KVM & HVF dtb_compatible value

target/arm: Correct KVM & HVF dtb_compatible value

Linux kernel knows how to parse "arm,armv8", not "arm,arm-v8".

See arch/arm64/boot/dts/foundation-v8.dts:

  https://github.com/torvalds/linux/commit/90556ca1ebdd

Cc: qemu-stable@nongnu.org
Fixes: 26861c7ce06 ("target-arm: Add minimal KVM AArch64 support")
Fixes: 585df85efea ("hvf: arm: Implement -cpu host")
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250623121845.7214-10-philmd@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit a412575837b6a46584fba891e3706e87bd09a3e6)
(Mjt: context fix in target/arm/kvm.c)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>