tests: logging/dictionary: filter for backend

Since only the UART backend supports output in hexidecimal form
with dictionary logging, so filter for that or else the pytest
would fail due to none, or wrong captured output.

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

tests/subsys/logging/dictionary/testcase.yaml

@@ -1,13 +1,8 @@
 common:
-  # For twister runs, the following arch/platforms use logging backends
-  # which do not output dictionary logging in hexidecimal format,
-  # and thus cannot be used for testing. Currently, only UART
-  # logging backend does that.
-  arch_exclude:
-    - posix
-  platform_exclude:
-    - qemu_xtensa
-    - qemu_xtensa/dc233c/mmu
+  # For twister runs, only logging backends with in hexidecimal format
+  # are supported. Currently, only UART logging backend does that.
+  filter: CONFIG_LOG_BACKEND_UART and CONFIG_LOG_BACKEND_UART_OUTPUT_DICTIONARY
+          and CONFIG_LOG_BACKEND_UART_OUTPUT_DICTIONARY_HEX
 tests:
   logging.dictionary:
     tags: logging