[SCSI] ips: sg chaining support to the path to non I/O commands

I overlooked ips_scmd_buf_write and ips_scmd_buf_read when I converted
ips to use the data buffer accessors.

ips is unlikely to use sg chaining (especially in this path) since a)
this path is used only for non I/O commands (with little data
transfer), b) ips's sg_tablesize is set to just 17.

Thanks to Tim Pepper for testing this patch.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Mark Salyzyn <Mark_Salyzyn@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>