dediprog: Fix small, unaligned reads

This never was a use case until now but the `--fmap` code makes it
obvious: Unaligned reads that were smaller than the `chunksize` here,
were extended without considering the length of the buffer read into.

With that fixed we run into the next problem: dediprog_spi_bulk_read()
shouldn't report an error when an empty read is unaligned.

Change-Id: Ie12b62499ebfdb467d5126c00d327c76077ddead
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/30051
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
---
M dediprog.c
1 file changed, 4 insertions(+), 4 deletions(-)