tools/libs/guest: Fix build following libx86 changes

I appear to have lost this hunk somewhere...

Fixes: 1b67fccf3b ("libx86: Update library API for cpu_policy")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>

tools/libs/guest/xg_cpuid_x86.c

@@ -555,7 +555,7 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
             const uint32_t *dfs;
 
             if ( !test_bit(b, disabled_features) ||
-                 !(dfs = x86_cpuid_lookup_deep_deps(b)) )
+                 !(dfs = x86_cpu_policy_lookup_deep_deps(b)) )
                 continue;
 
             for ( i = 0; i < ARRAY_SIZE(disabled_features); ++i )