STM32 MBEDTLS: create mbedtls_device.h for all F756 targets

Author: jeromecoutant

features/mbedtls/targets/TARGET_STM/TARGET_STM32F7/TARGET_NUCLEO_F756ZG/mbedtls_device.h renamed to features/mbedtls/targets/TARGET_STM/TARGET_STM32F756xG/mbedtls_device.h

@@ -21,8 +21,10 @@
 #define MBEDTLS_DEVICE_H
 
 #define MBEDTLS_AES_ALT
-#define MBEDTLS_SHA1_ALT
-
 #define MBEDTLS_MD5_ALT
+#define MBEDTLS_SHA1_ALT
+#define MBEDTLS_SHA256_ALT
+// #define MBEDTLS_CCM_ALT // not fully supported yet
+// #define MBEDTLS_GCM_ALT // not fully supported yet
 
 #endif /* MBEDTLS_DEVICE_H */