scsi: aha1740: Avoid over-read of sense buffer

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally reading across neighboring array fields.

SCtmp->sense_buffer is 96 bytes, but ecbptr->sense is 14 bytes. Instead of
over-reading ecbptr->sense, copy only the actual contents and zero pad the
remaining bytes, avoiding potential over-reads.

Link: https://lore.kernel.org/r/20210616212437.1727088-1-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>