tpm: Move tpm_cleanup() to right place

As Emulator TPM backend uses chardev, tpm cleanup should happen before chardev
similar to other vhost-users.
Signed-off-by: Amarnath Valluri <amarnath.valluri@intel.com>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

tpm.c

@@ -172,7 +172,6 @@ int tpm_init(void)
         return -1;
     }
 
-    atexit(tpm_cleanup);
     return 0;
 }
 

vl.c

@@ -4905,6 +4905,7 @@ int main(int argc, char **argv, char **envp)
     res_free();
 
     /* vhost-user must be cleaned up before chardevs.  */
+    tpm_cleanup();
     net_cleanup();
     audio_cleanup();
     monitor_cleanup();