regmap: Remove default cache sync implementation

It's not used as all cache types have sync operations so it's just dead
code which never gets tested.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/regcache.c

@@ -254,12 +254,11 @@ EXPORT_SYMBOL_GPL(regcache_write);
 int regcache_sync(struct regmap *map)
 {
 	int ret = 0;
-	unsigned int val;
 	unsigned int i;
 	const char *name;
 	unsigned int bypass;
 
-	BUG_ON(!map->cache_ops);
+	BUG_ON(!map->cache_ops || !map->cache_ops->sync);
 
 	mutex_lock(&map->lock);
 	/* Remember the initial bypass state */
@@ -284,24 +283,8 @@ int regcache_sync(struct regmap *map)
 	}
 	map->cache_bypass = 0;
 
-	if (map->cache_ops->sync) {
-		ret = map->cache_ops->sync(map);
-	} else {
-		for (i = 0; i < map->num_reg_defaults; i++) {
-			ret = regcache_read(map, i, &val);
-			if (ret < 0)
-				goto out;
-			map->cache_bypass = 1;
-			ret = _regmap_write(map, i, val);
-			map->cache_bypass = 0;
-			if (ret < 0)
-				goto out;
-			dev_dbg(map->dev, "Synced register %#x, value %#x\n",
-				map->reg_defaults[i].reg,
-				map->reg_defaults[i].def);
-		}
+	ret = map->cache_ops->sync(map);
 
-	}
 out:
 	trace_regcache_sync(map->dev, name, "stop");
 	/* Restore the bypass state */