Rename pw_dumb_io to pw_sys_io

Rename pw_dumb_io facade and backends to use the more deliberate name
pw_sys_io moving forward.

Change-Id: I968480715967ab8de491856afa1b7692b973ed7e
diff --git a/pw_log_basic/BUILD b/pw_log_basic/BUILD
index fd9105d..ad7ac07 100644
--- a/pw_log_basic/BUILD
+++ b/pw_log_basic/BUILD
@@ -35,8 +35,8 @@
         "public_overrides",
     ],
     deps = [
-        "//pw_dumb_io",
         "//pw_log:facade",
         "//pw_string",
+        "//pw_sys_io",
     ],
 )