i2c: muxes always lock the parent adapter

Instead of checking for i2c parent adapters for every lock/unlock, simply
override the locking for muxes to always lock/unlock the parent adapter
directly.

Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 7ef5bd0..afdee66 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -962,12 +962,7 @@
 static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
 				 unsigned int flags)
 {
-	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
-
-	if (parent)
-		i2c_lock_adapter(parent);
-	else
-		rt_mutex_lock(&adapter->bus_lock);
+	rt_mutex_lock(&adapter->bus_lock);
 }
 
 /**
@@ -979,12 +974,7 @@
 static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
 				   unsigned int flags)
 {
-	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
-
-	if (parent)
-		return parent->trylock_bus(parent, flags);
-	else
-		return rt_mutex_trylock(&adapter->bus_lock);
+	return rt_mutex_trylock(&adapter->bus_lock);
 }
 
 /**
@@ -996,12 +986,7 @@
 static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
 				   unsigned int flags)
 {
-	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
-
-	if (parent)
-		i2c_unlock_adapter(parent);
-	else
-		rt_mutex_unlock(&adapter->bus_lock);
+	rt_mutex_unlock(&adapter->bus_lock);
 }
 
 static void i2c_dev_set_name(struct i2c_adapter *adap,