MIPS32R3 provides the EXT instruction to extract bits from

registers. As the AES table is already 1K aligned we can
use it everywhere and speedup table address calculation by
10%. Performance numbers:

decryption         16B       64B      256B     1024B     8192B
-------------------------------------------------------------------
aes-256-cbc   5636.84k  6443.26k  6689.02k  6752.94k  6766.59k bef.
aes-256-cbc   6200.31k  7195.71k  7504.30k  7585.11k  7599.45k aft.
-------------------------------------------------------------------
aes-128-cbc   7313.85k  8653.67k  9079.55k  9188.35k  9205.08k bef.
aes-128-cbc   7925.38k  9557.99k 10092.37k 10232.15k 10272.77k aft.

encryption         16B       64B      256B     1024B     8192B
-------------------------------------------------------------------
aes-256 cbc   6009.65k  6592.70k  6766.59k  6806.87k  6815.74k bef.
aes-256 cbc   6643.93k  7388.69k  7605.33k  7657.81k  7675.90k aft.
-------------------------------------------------------------------
aes-128 cbc   7862.09k  8892.48k  9214.04k  9291.78k  9311.57k bef.
aes-128 cbc   8639.29k  9881.17k 10265.86k 10363.56k 10392.92k aft.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8206)