TPL: TM2: f_thor: Allow to download 4GB images

TPL: TM2: f_thor: Allow to download 4GB images

This commit fixes 2GB file size limit for thor downloader.

The application on host side sends the downloaded file size as 32-bit
unsigned value. But the thor implementation on U-Boot side interpreted
this as signed value. This caused an error for files with size greater
than 2GB.

This commit fixes the data types in code, which allows to send file
of size 4GB.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
[m.szyprowski: ported from tizen.org and fixed 64bit issues]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>