[SCSI] scsi_dh: suppress comparison warning

On Mon, 2008-09-22 at 14:56 -0700, akpm@linux-foundation.org wrote:
> From: Andrew Morton <akpm@linux-foundation.org>
>
> s390:
>
> drivers/scsi/device_handler/scsi_dh_emc.c: In function 'parse_sp_info_reply':
> drivers/scsi/device_handler/scsi_dh_emc.c:179: warning: comparison is always false due to limited range of data type
>
> because chars are unsigned, I assume.

Fix by making csdev->buffer explicitly an unsigned char and dropping
the < 0 test.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>