espressif: Enable signature verification (RSA, EC256 and ED25519)

MbedTLS and Tinycrypt security lib options added to Espressif's
configuration and build.

Signed-off-by: Almir Okato <almir.okato@espressif.com>
diff --git a/boot/espressif/include/os/os_malloc.h b/boot/espressif/include/os/os_malloc.h
index 1a6a6dc..6ca5c46 100644
--- a/boot/espressif/include/os/os_malloc.h
+++ b/boot/espressif/include/os/os_malloc.h
@@ -7,3 +7,5 @@
 #pragma once
 
 #include <stdlib.h>
+
+void os_heap_init(void);