Fix compilation errors after updating

Fix compilation errorsthat happened after new code introduced
by updating the branch. Replaced `exit` label with `cleanup`.
diff --git a/programs/pkey/key_app.c b/programs/pkey/key_app.c
index 4dbbdfb..f57dba1 100644
--- a/programs/pkey/key_app.c
+++ b/programs/pkey/key_app.c
@@ -200,7 +200,7 @@
                 ( ret = mbedtls_rsa_export_crt( rsa, &DP, &DQ, &QP ) )      != 0 )
             {
                 mbedtls_printf( " failed\n  ! could not export RSA parameters\n\n" );
-                goto exit;
+                goto cleanup;
             }
 
             MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( "N:  ", &rsa->N, 16, NULL ) );
@@ -258,7 +258,7 @@
                                             NULL, &E ) ) != 0 )
             {
                 mbedtls_printf( " failed\n  ! could not export RSA parameters\n\n" );
-                goto exit;
+                goto cleanup;
             }
             MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( "N:  ", &rsa->N, 16, NULL ) );
             MBEDTLS_MPI_CHK( mbedtls_mpi_write_file( "E:  ", &rsa->E, 16, NULL ) );