Record the number of header bytes skipped in the total bytes read field.

This is needed for the initramfs parsing code to find the end of the zip file.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>