rsa: Introduce rsa driver

Add rsa driver based on the implementation in aspeed zephyr sdk.
The patch also add functional test and rsa test data generator.

How to verify driver:

1. You may use the existing test vectors in tests/functional/rsa_test_vec.rs, or
2. Generate fresh vectors by running:
     python3 scripts/rsa_test_vec_gen.py > src/tests/functional/rsa_test_vec.rs
3. Build and run the image

Signed-off-by: Steven Lee <steven_lee@aspeedtech.com>

Author: stevenlee7189

src/main.rs

@@ -148,6 +148,9 @@ fn main() -> ! {
     let mut rsa = AspeedRsa::new(&secure, delay);
     run_rsa_tests(&mut uart_controller, &mut rsa);
 
+    let mut rsa = AspeedRsa::new(&secure, delay);
+    run_rsa_tests(&mut uart_controller, &mut rsa);
+
     test_wdt(&mut uart_controller);
     // Initialize the peripherals here if needed
     loop {}