lib/crypto: mips: Drop optimized MD5 code

lib/crypto: mips: Drop optimized MD5 code

MD5 is obsolete.  Continuing to maintain architecture-optimized
implementations of MD5 is unnecessary and risky.  It diverts resources
from the modern algorithms that are actually important.

While there was demand for continuing to maintain the PowerPC optimized
MD5 code to accommodate userspace programs that are misusing AF_ALG
(https://lore.kernel.org/linux-crypto/c4191597-341d-4fd7-bc3d-13daf7666c41@csgroup.eu/),
no such demand has been seen for the MIPS Cavium Octeon optimized MD5
code.  Note that this code runs on only one particular line of SoCs.

Thus, let's drop it and focus effort on the more modern SHA algorithms,
which already have optimized code for the same SoCs.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260326204824.62010-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>