ipr: Enable SIS pipe commands for SIS-32 devices.

Remove unnecessary check that disabled SIS pipe commands for SIS-32
devices.  This change was sufficient to enable raw mode and send SIS
pipe commands for a 57B3 device.

Fixes: f8ee25d7 ("ipr: AF DASD raw mode implementation in ipr driver")
Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>