pw_kvs: Fix printf-style format strings

Fix a few variables so they don't assume the underlying type of
uint32_t.

Change-Id: I3e78c82898ecda7a04e4ba31da46bb3b299db5be
diff --git a/pw_kvs/entry_cache.cc b/pw_kvs/entry_cache.cc
index 64f3bec..447417d 100644
--- a/pw_kvs/entry_cache.cc
+++ b/pw_kvs/entry_cache.cc
@@ -129,8 +129,8 @@
     // this same key.
     for (Address existing_address : addresses(index)) {
       if (existing_address / sector_size_bytes == address / sector_size_bytes) {
-        PW_LOG_DEBUG("Multiple Redundant entries in same sector %zu",
-                     address / sector_size_bytes);
+        PW_LOG_DEBUG("Multiple Redundant entries in same sector %u",
+                     unsigned(address / sector_size_bytes));
         return Status::DATA_LOSS;
       }
     }