GT-P5220: Sendpacket fix

New option --zero-packet-fix: Support for Galaxy Tab 3 GT-P5220 and similar devices.


# BUG: GT-P5220
$ heimdall print-pit --verbose
...
Initialising protocol...
Protocol initialisation successful.

Beginning session...
ERROR: libusb error -7 whilst receiving packet. Retrying...

# OK: GT-P5220
$ heimdall print-pit --verbose --zero-packet-fix
...
Initialising protocol...
Protocol initialisation successful.

Beginning session...

Some devices may take up to 2 minutes to respond.
Please be patient!

Session begun.

Downloading device's PIT file...
PIT file download successful.
...

###
Tested with Galaxy Tab 3 GT-P5220.
Cpu: Intel Atom Z2560
USB:
idVendor           0x04e8
idProduct          0x685d