Change return value on error.

On wrong parameters a error is signalized to the calling function.

Change-Id: I484443fdb39938e20382edc9246d5ec546a5c960
Signed-off-by: Mathias K <kesmtp@freenet.de>
Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>
Reviewed-on: http://openocd.zylin.com/282
Tested-by: jenkins
Reviewed-by: Øyvind Harboe <oyvindharboe@gmail.com>

src/flash/nor/virtual.c

@@ -55,8 +55,7 @@ FLASH_BANK_COMMAND_HANDLER(virtual_flash_bank_command)
 {
 	if (CMD_ARGC < 7)
 	{
-		LOG_WARNING("incomplete flash_bank virtual configuration");
-		return ERROR_FLASH_OPERATION_FAILED;
+		return ERROR_COMMAND_SYNTAX_ERROR;
 	}
 
 	/* get the master flash bank */