Initialize mbedtls_x509write_csr struct before USE_PSA_INIT(), mbedtls_x509write_csr_free() will crash if uninitialized

When USE_PSA_INIT() failed because lack of seedfile, mbedtls_x509write_csr_free()
crashed when called on an unitialized mbedtls_x509write_csr struct.

This moves mbedtls_x509write_csr_init before calling USE_PSA_INIT(),
which could probably fail, and uses the same flow in x509_csr_check()
and x509_csr_check_opaque().

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index d6879a2..12c8f39 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -93,10 +93,11 @@
 
     memset( &rnd_info, 0x2a, sizeof( mbedtls_test_rnd_pseudo_info ) );
 
+    mbedtls_x509write_csr_init( &req );
+
     mbedtls_pk_init( &key );
     TEST_ASSERT( mbedtls_pk_parse_keyfile( &key, key_file, NULL ) == 0 );
 
-    mbedtls_x509write_csr_init( &req );
     mbedtls_x509write_csr_set_md_alg( &req, md_type );
     mbedtls_x509write_csr_set_key( &req, &key );
     TEST_ASSERT( mbedtls_x509write_csr_set_subject_name( &req, subject_name ) == 0 );
@@ -156,9 +157,12 @@
     const char *subject_name = "C=NL,O=PolarSSL,CN=PolarSSL Server 1";
     mbedtls_test_rnd_pseudo_info rnd_info;
 
-    PSA_INIT( );
     memset( &rnd_info, 0x2a, sizeof( mbedtls_test_rnd_pseudo_info ) );
 
+    mbedtls_x509write_csr_init( &req );
+
+    USE_PSA_INIT( );
+
     md_alg_psa = mbedtls_psa_translate_md( (mbedtls_md_type_t) md_type );
     TEST_ASSERT( md_alg_psa != MBEDTLS_MD_NONE );
 
@@ -166,7 +170,6 @@
     TEST_ASSERT( mbedtls_pk_parse_keyfile( &key, key_file, NULL ) == 0 );
     TEST_ASSERT( mbedtls_pk_wrap_as_opaque( &key, &key_id, md_alg_psa ) == 0 );
 
-    mbedtls_x509write_csr_init( &req );
     mbedtls_x509write_csr_set_md_alg( &req, md_type );
     mbedtls_x509write_csr_set_key( &req, &key );
     TEST_ASSERT( mbedtls_x509write_csr_set_subject_name( &req, subject_name ) == 0 );