Don't use cycle counter on ARM32

[dstebila]

Fixes #1483.

• [No] Does this PR change the input/output behaviour of a cryptographic algorithm (i.e., does it change known answer test values)? (If so, a version bump will be required from x.y.z to x.(y+1).0.)
• [No] Does this PR change the list of algorithms available -- either adding, removing, or renaming? Does this PR otherwise change an API? (If so, PRs in oqs-provider, OQS-OpenSSL, OQS-BoringSSL, and OQS-OpenSSH will also need to be ready for review and merge by the time this is merged.)

[baentsch]

Logically LGTM as the #define else branches take over -- just wondering whether it'd also be sensible to purge all references to "_OQS_RASPBERRY_PI" then (?)

[vt-alt]

Thanks much!