KVM: selftests: Zero out the correct page in the Hyper-V features test

Fix an apparent copy-paste goof in hyperv_features where hcall_page
(which is two pages, so technically just the first page) gets zeroed
twice, and hcall_params gets zeroed none times.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210622200529.3650424-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/x86_64/hyperv_features.c

@@ -630,7 +630,7 @@ int main(void)
 	memset(addr_gva2hva(vm, hcall_page), 0x0, 2 * getpagesize());
 
 	hcall_params = vm_vaddr_alloc(vm, getpagesize(), 0x20000, 0, 0);
-	memset(addr_gva2hva(vm, hcall_page), 0x0, getpagesize());
+	memset(addr_gva2hva(vm, hcall_params), 0x0, getpagesize());
 
 	vcpu_args_set(vm, VCPU_ID, 2, addr_gva2gpa(vm, hcall_page), hcall_params);
 	vcpu_enable_cap(vm, VCPU_ID, &cap);