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: 26861c7ce0 ("target-arm: Add minimal KVM AArch64 support")
Fixes: 585df85efe ("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>

target/arm/hvf/hvf.c

@@ -883,7 +883,7 @@ static bool hvf_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     hv_vcpu_exit_t *exit;
     int i;
 
-    ahcf->dtb_compatible = "arm,arm-v8";
+    ahcf->dtb_compatible = "arm,armv8";
     ahcf->features = (1ULL << ARM_FEATURE_V8) |
                      (1ULL << ARM_FEATURE_NEON) |
                      (1ULL << ARM_FEATURE_AARCH64) |

target/arm/kvm.c

@@ -289,7 +289,7 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     }
 
     ahcf->target = init.target;
-    ahcf->dtb_compatible = "arm,arm-v8";
+    ahcf->dtb_compatible = "arm,armv8";
     int fd = fdarray[2];
 
     err = get_host_cpu_reg(fd, ahcf, ID_AA64PFR0_EL1_IDX);