psa_crypto_init: set the global initialized flag

library/psa_crypto.c

diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index e264990..ea25c49 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1288,6 +1288,8 @@
     if( ret != 0 )
         goto exit;
 
+    global_data.initialized = 1;
+
 exit:
     if( ret != 0 )
         mbedtls_psa_crypto_free( );