KVM: selftests: Use kvm_has_cap(), not kvm_check_cap(), where possible

Replace calls to kvm_check_cap() that treat its return as a boolean with
calls to kvm_has_cap().  Several instances of kvm_check_cap() were missed
when kvm_has_cap() was introduced.

Reported-by: Andrew Jones <drjones@redhat.com>
Fixes: 3ea9b809 ("KVM: selftests: Add kvm_has_cap() to provide syntactic sugar")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220613161942.1586791-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>