ipq40xx: use neon crypto drivers

ipq40xx: use neon crypto drivers

This adds the neon based implementations of AES & SHA256.

For AES, according to the kernel config help:

Use a faster and more secure NEON based implementation of AES in CBC,
CTR and XTS modes.
Bit sliced AES gives around 45% speedup on Cortex-A15 for CTR mode
and for XTS mode encryption, CBC and XTS mode decryption speedup is
around 25%. (CBC encryption speed is not affected by this driver.)
This implementation does not rely on any lookup tables so it is
believed to be invulnerable to cache timing attacks.
...
The observed speedups on ipq40xx are more modest: speedup is around 20%
for CTR mode and for XTS mode encryption, CBC and XTS mode decryption
speedup is around 10%. Measurements were made using tcrypt, with
1024-bytes blocks for CTR & CBC, and 4096-bytes for XTS.
The aes-neon-bs driver uses a fallback for CBC encryption; that fallback
could be either the generic driver written in C, or the scalar arm-asm
one.  Even though aes-arm is 1.9% slower, it is more resilient to timing
attacks (the reason for being slower), so it is being included here.

The neon sha256 module increases performance over the generic module by
33%.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
[Enable only ciphers for now, reorder patch in series to help bisect
as new symbols could lead to build failures, 5.4]
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>