staging: ccree: fix buffer copy

Fix a bug where the copying of scatterlist buffers incorrectly
ignored bytes to skip in a scatterlist and ended 1 byte short.

This fixes testmgr hmac and hash test failures currently obscured
by hash import/export not being supported.

Fixes: abefd674

 ("staging: ccree: introduce CryptoCell HW driver").

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>