tests: cmsis_nn: reduce architecture scope

Filters already only allow arm and native, so exclude everything else
very early and reduce churn and build time.

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

tests/lib/cmsis_nn/testcase.yaml

@@ -1,5 +1,7 @@
 tests:
   libraries.cmsis_nn:
+    arch_allow:
+      - arm
     filter: CONFIG_CPU_CORTEX_M and CONFIG_FULL_LIBC_SUPPORTED
     integration_platforms:
       - frdm_k64f