KVM: x86: Assign correct value to array.maxnent

Delay the assignment of array.maxnent to use correct value for the case
cpuid->nent > KVM_MAX_CPUID_ENTRIES.

Fixes: e53c95e8

 ("KVM: x86: Encapsulate CPUID entries and metadata in struct")
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200604041636.1187-1-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>