tests: fs: add more tags

Add module names as tags, to trigger CI on those tests when module has
changed.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

tests/posix/fs/testcase.yaml

@@ -5,6 +5,7 @@ common:
   tags:
     - posix
     - filesystem
+    - fatfs
   min_ram: 128
   modules:
     - fatfs

tests/subsys/fs/fat_fs_api/testcase.yaml

@@ -1,5 +1,7 @@
 common:
-  tags: filesystem
+  tags:
+    - filesystem
+    - fatfs
   modules:
     - fatfs
 tests:

tests/subsys/logging/log_backend_fs/testcase.yaml

@@ -6,6 +6,7 @@ common:
     - backend
     - filesystem
     - fs
+    - littlefs
 tests:
   logging.log_backend_fs.automounted:
     platform_allow: