crypto: tegra - fix missing unlock on error case

Add the missing unlock on the error handling path in function
tegra_aes_get_random() and tegra_aes_rng_reset().

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>