Fix DTR/RTS reset/isp signals for SYSFS_GPIO_SUPPORT

[domenpk]

The default SYSFS_GPIO_SUPPORT define broke DTS/RTS over serial port (when -control was used, it failed when it couldn't open GPIO files).

Fixing by rearranging code. If -control is passed, DTS/RTS is used, otherwise SYSFS is any -gpio options are set, otherwise none.