[nrf fromtree] tests: debug: cpu_load: Extend filtering with riscv

Allow test execution for riscv since it now supports cpu_load module.

Signed-off-by: Krzysztof Chruściński <[email protected]>
(cherry picked from commit 29bc28a)

Author: nordic-krch

tests/subsys/debug/cpu_load/testcase.yaml

@@ -1,7 +1,9 @@
 common:
   tags: cpu_load
-  arch_allow: arm
-  filter: CONFIG_CPU_CORTEX_M
+  arch_allow:
+    - arm
+    - riscv
+  filter: CONFIG_CPU_LOAD
 tests:
   debug.cpu_load:
     integration_platforms: