Remove NULL-ing of passed in SSL context in ssl_populate_transform()

Remove a piece of code that was meant to ensure non-usage of the ssl
context under conditions where it should not be used, as this now makes
less sense and also triggers coverity.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 827b7fb..0476a9f 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -8159,14 +8159,6 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
 #endif
 
-#if !defined(MBEDTLS_DEBUG_C) && \
-    !defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
-    if (ssl->f_export_keys == NULL) {
-        ssl = NULL; /* make sure we don't use it except for these cases */
-        (void) ssl;
-    }
-#endif
-
     /*
      * Some data just needs copying into the structure
      */
@@ -8438,7 +8430,7 @@
         goto end;
     }
 
-    if (ssl != NULL && ssl->f_export_keys != NULL) {
+    if (ssl->f_export_keys != NULL) {
         ssl->f_export_keys(ssl->p_export_keys,
                            MBEDTLS_SSL_KEY_EXPORT_TLS12_MASTER_SECRET,
                            master, 48,