[SCSI] 3w-9xxx, 3w-xxxx: memset not needed in probe

The memory return from scsi_host_alloc is alloced by kzalloc, which is
already zero initilized, so memset not needed.

Signed-off-by: Denis Cheng <crquan@gmail.com>
Cc: Adam Radford <linuxraid@amcc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>