Makfile: Use correct file paths and set variables

[paddatrapper]

Makes the firmware build correctly and flash the FX2 chip. Also added instructions to the README for building and flashing the firmware

[paddatrapper]

The only issue is that the hdmi2usb-mode-switch command requires root permissions to flash the firmware, thus using the Makefile means that everything is built as root (or requires running twice). This needs fixing

If not run with root, it fails at

hdmi2usb-mode-switch --load-fx2-firmware hdmi2usb/hdmi2usb.hex
Traceback (most recent call last):
  File "/usr/bin/hdmi2usb-mode-switch", line 11, in <module>
    load_entry_point('hdmi2usb.modeswitch==0+unknown', 'console_scripts', 'hdmi2usb-mode-switch')()
  File "/usr/share/hdmi2usb-mode-switch/hdmi2usb/modeswitch/cli.py", line 255, in main
    verbose=args.verbose)
  File "/usr/share/hdmi2usb-mode-switch/hdmi2usb/modeswitch/boards.py", line 109, in load_fx2
    board.dev.detach()
  File "/usr/share/hdmi2usb-mode-switch/hdmi2usb/modeswitch/lsusb.py", line 154, in detach
    open(unbind_path, "w").write(interface)
PermissionError: [Errno 13] Permission denied: '/sys/bus/usb/devices/2-2:1.0/driver/unbind'
Makefile.fx2:39: recipe for target 'load-fx2' failed
make: *** [load-fx2] Error 1

[mithro]

hdmi2usb-mode-switch has three options;

• run as root
• install the "unbind-helper" as a setuid binary
• install the "udev rules" which set the permissions of the unbind

[mithro]

Looks good to me, one small change - Can you please updated your commit messages to start with a capital letter?

[paddatrapper]

Fixed. Added the mode-switch info to the README

[mithro]

Could you also send a pull request for the mode-switch repo with the extra mode-switch root info?