M467: Fix mbedtls H/W acceleration build error

[ccli8]

Summary of changes

For Nuvoton M467, this fixes mbedtls H/W acceleration build error on migration to Mbed CE.

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Pull request type

[X] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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[multiplemonomials]

Whoops, good catch!