arm64/crypto: issue aese/aesmc instructions in pairs

This changes the AES core transform implementations to issue aese/aesmc
(and aesd/aesimc) in pairs. This enables a micro-architectural optimization
in recent Cortex-A5x cores that improves performance by 50-90%.

Measured performance in cycles per byte (Cortex-A57):

                CBC enc         CBC dec         CTR
  before        3.64            1.34            1.32
  after         1.95            0.85            0.93

Note that this results in a ~5% performance decrease for older cores.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Will Deacon <[email protected]>

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