crypto: sun8i-ss - Remove crypto_rng interface

In the Linux kernel, the following vulnerability has been resolved: crypto: sun8i-ss - Remove crypto_rng interface Since the crypto_rng interface for hardware PRNGs is unused and is redundant with hwrng and the actual Linux RNG, it's being phased out. Most drivers for it were already removed. Go ahead and remove the sun8i-ss support which is one of the only remaining ones. As usual for crypto_rng, this driver was also buggy: its ->generate() function had a use-after-free vulnerability due to using wait_for_completion_interruptible_timeout() without handling shutting down the DMA operation if a signal is sent. Also, it had a buffer overread bug in the line 'memcpy(ctx->seed, d + dlen, ctx->slen);'. There's no point in fixing these bugs separately only to remove the code anyway, so this commit is marked with Fixes and Cc stable.