i386/cpuid: Decrease cpuid_i when skipping CPUID leaf 1F

Existing code misses a decrement of cpuid_i when skip leaf 0x1F.
There's a blank CPUID entry(with leaf, subleaf as 0, and all fields
stuffed 0s) left in the CPUID array.

It conflicts with correct CPUID leaf 0.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by:Yang Weijiang <weijiang.yang@intel.com>
Message-ID: <20240125024016.2521244-2-xiaoyao.li@intel.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/kvm/kvm.c

@@ -1914,6 +1914,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         }
         case 0x1f:
             if (env->nr_dies < 2) {
+                cpuid_i--;
                 break;
             }
             /* fallthrough */