sound: mpu401.c: make return of 0 explicit

Delete unnecessary local variable whose value is always 0 and that hides
the fact that the result is always 0.

A simplified version of the semantic patch that fixes this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
local idexpression ret;
expression e;
position p;
@@

-ret = 0;
... when != ret = e
return
- ret
+ 0
  ;
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/oss/mpu401.c

@@ -567,7 +567,6 @@ static int mpu401_out(int dev, unsigned char midi_byte)
 static int mpu401_command(int dev, mpu_command_rec * cmd)
 {
 	int i, timeout, ok;
-	int ret = 0;
 	unsigned long   flags;
 	struct mpu_config *devc;
 
@@ -644,7 +643,6 @@ static int mpu401_command(int dev, mpu_command_rec * cmd)
 			}
 		}
 	}
-	ret = 0;
 	cmd->data[0] = 0;
 
 	if (cmd->nr_returns)
@@ -666,7 +664,7 @@ static int mpu401_command(int dev, mpu_command_rec * cmd)
 		}
 	}
 	spin_unlock_irqrestore(&devc->lock,flags);
-	return ret;
+	return 0;
 }
 
 static int mpu_cmd(int dev, int cmd, int data)