target/mips: add Octeon COP2 crypto state

Add the common architectural state needed by Octeon's selector-driven
COP2 crypto interfaces. This includes storage for the base hash, AES,
CRC, GFM, 3DES, KASUMI, and overlapping HSH/SHA512/SHA3/SNOW3G/ZUC
selector windows.

Keep selector values and helper-local aliasing logic out of the CPU state
header so the state definition remains limited to architectural storage.
Helper code uses the same register banks instead of adding
non-architectural shadow state. Model the SHA3 view as a direct 25-lane
alias of the architectural HSH DAT/IV/SHA3_DAT24 storage.

Migrate the state in an Octeon-only subsection so non-Octeon CPU models
do not grow migration data.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20260608-mips-octeon-missing-insns-v2-v16-1-daef7a0d8b04@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>