Bluetooth: convert smp and selftest to crypto kpp API

* Convert both smp and selftest to crypto kpp API
* Remove module ecc as no more required
* Add ecdh_helper functions for wrapping kpp async calls

This patch has been tested *only* with selftest, which is called on
module loading.

Signed-off-by: Salvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig
index 06c31b9..68f951b 100644
--- a/net/bluetooth/Kconfig
+++ b/net/bluetooth/Kconfig
@@ -13,6 +13,7 @@
 	select CRYPTO_CMAC
 	select CRYPTO_ECB
 	select CRYPTO_SHA256
+	select CRYPTO_ECDH
 	help
 	  Bluetooth is low-cost, low-power, short-range wireless technology.
 	  It was designed as a replacement for cables and other short-range