Fix the memory allocation in test_suite_ssl

ASSERT_ALLOC calculates the size itself, and the parameter indicates number of elements.
```
mbedtls_calloc( sizeof( *( pointer ) ),  ( length ) );  
```
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 6664a79..cd356f5 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -873,9 +873,9 @@
     }
 
     cert = &( ep->cert );
-    ASSERT_ALLOC( cert->ca_cert, sizeof(mbedtls_x509_crt) );
-    ASSERT_ALLOC( cert->cert, sizeof(mbedtls_x509_crt) );
-    ASSERT_ALLOC( cert->pkey, sizeof(mbedtls_pk_context) );
+    ASSERT_ALLOC( cert->ca_cert, 1 );
+    ASSERT_ALLOC( cert->cert, 1 );
+    ASSERT_ALLOC( cert->pkey, 1 );
 
     mbedtls_x509_crt_init( cert->ca_cert );
     mbedtls_x509_crt_init( cert->cert );