domain_caps: Don't leak 'cpu0_id' in 'virSEVCapabilitiesFree'

Freeing the 'virSEVCapability' object leaked the 'cpu0_id' field since
its introduction.

Fixes: 0236e6154c
Signed-off-by: Peter Krempa <pkrempa@redhat.com>

src/conf/domain_capabilities.c

@@ -75,6 +75,7 @@ virSEVCapabilitiesFree(virSEVCapability *cap)
 
     g_free(cap->pdh);
     g_free(cap->cert_chain);
+    g_free(cap->cpu0_id);
     g_free(cap);
 }