Add EFI_RNG_PROTOCOL

[gelven4sec]

Hi guys,

I'm writing a pretty special uefi application where having a random seed would be great.

To do so, the EFI_RNG_PROTOCOL seems to be what I need, you can find the description page 2139 of the uefi spec document.

It's two functions that would look like this :

fn get_info(&self, rng_algorithm_list_size: usize, rng_algorithm_list: &mut [u8]) -> Result {...}

fn get_rng(&self, Option<RngAlgorithm>, rng_value_length: usize, rng_value: &mut [u8]) -> Result {...}

After reading the contributing github page, i think I should try to implement this myself.

I'll keep you in touch here if I need your help.