config: Fix Doxygen link to MBEDTLS_PARAM_FAILED
Don't use `#` for linking to function-like macros.
* the function mbedtls_param_failed() in your application.
* See `platform_util.h` for its prototype.
* - If you enable the macro #MBEDTLS_CHECK_PARAMS_ASSERT, then the
- * library defines #MBEDTLS_PARAM_FAILED(\c cond) to be `assert(cond)`.
+ * library defines MBEDTLS_PARAM_FAILED(\c cond) to be `assert(cond)`.
* You can still supply an alternative definition of
* MBEDTLS_PARAM_FAILED(), which may call `assert`.
* - If you define a macro MBEDTLS_PARAM_FAILED() before including `config.h`
