Move handling of 'SE' drivers into driver wrappers

This is a more natural place for handling the drivers belonging to the
'previous' SE driver spec. It makes for a cleaner psa_crypto.c, and
potentially an easier overview of how to migrate from the old SE driver
interface to the 'opaque accelerator' interface.

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index af8a7a9..460b9df 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3638,10 +3638,6 @@
 {
     psa_key_slot_t *slot;
     psa_status_t status;
-#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
-    const psa_drv_se_t *drv;
-    psa_drv_se_context_t *drv_context;
-#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
 
     *signature_length = signature_size;
     /* Immediately reject a zero-length signature buffer. This guarantees
@@ -3671,24 +3667,7 @@
     if( status != PSA_ERROR_NOT_SUPPORTED )
         goto exit;
 
-#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
-    if( psa_get_se_driver( slot->attr.lifetime, &drv, &drv_context ) )
-    {
-        if( drv->asymmetric == NULL ||
-            drv->asymmetric->p_sign == NULL )
-        {
-            status = PSA_ERROR_NOT_SUPPORTED;
-            goto exit;
-        }
-        status = drv->asymmetric->p_sign( drv_context,
-                                          slot->data.se.slot_number,
-                                          alg,
-                                          hash, hash_length,
-                                          signature, signature_size,
-                                          signature_length );
-    }
-    else
-#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+    /* If the operation was not supported by any accelerator, try fallback. */
 #if defined(MBEDTLS_RSA_C)
     if( slot->attr.type == PSA_KEY_TYPE_RSA_KEY_PAIR )
     {