i2c: pmcmsp: return message count on master_xfer success

Returning zero is wrong in this case.
Signed-off-by: NPeter Rosin <peda@axentia.se>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Fixes: 1b144df1 ("i2c: New PMC MSP71xx TWI bus driver")

drivers/i2c/busses/i2c-pmcmsp.c

@@ -567,7 +567,7 @@ static int pmcmsptwi_master_xfer(struct i2c_adapter *adap,
 		return -1;
 	}
 
-	return 0;
+	return num;
 }
 
 static u32 pmcmsptwi_i2c_func(struct i2c_adapter *adapter)