s3: torture: adjust SMB1 cli_splice() test sizes

s3: torture: adjust SMB1 cli_splice() test sizes

The test writes 20M and then splices just over 1M (13M is intended,
but there's a 1024*0124 typo). Fix the type and reduce the size of the
dataset to make it run faster - cli_splice works with 1M chunks
(SPLICE_BLOCK_SIZE), and the reproducer only requires that the splice
size is not chunk-aligned.

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Sat Jul 14 00:14:13 CEST 2018 on sn-devel-144