libxc: fix leak in xc_offline_page error path

Avoid leaking the mapping of the m2p in one of the possible failure cases.

Coverity CID 1351225

Signed-off-by: Harmandeep Kaur <write.harmandeep@gmail.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/libxc/xc_offline_page.c

@@ -504,7 +504,7 @@ int xc_exchange_page(xc_interface *xch, int domid, xen_pfn_t mfn)
     if ( xc_map_domain_meminfo(xch, domid, &minfo) )
     {
         PERROR("Could not map domain's memory information\n");
-        return -1;
+        goto failed;
     }
 
     /* For translation macros */