uboot-phytec

usb:gadget:f_thor: download_tail(): remove dfu_write with 0 size

Since dfu_flush() can write raw data, dfu_write() with zero size
can be removed from download_tail() in thor gadget.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Marek Vasut <marex@denx.de>