imx_sdp: add writeable_header to struct load_desc
imx_sdp: add writeable_header to struct load_desc

This header is the one modified. The current file buffer
is not changed. So, saving the buffer is no longer necessary.

Also, adding fetch_data common routine to make data
easier to find.

Signed-off-by: Troy Kisky <debfc29e3a9e989b865b88f1f207951588bac6b3@boundarydevices.com>

boundarydevices/imx_usb_loader,bwalle/imx_usb_loader