[SCSI] ips: use sg buffer copy helper funcitons

This rewrites ips_scmd_buf_write/read with scsi_sg_copy_from/to_buffer
respectively.

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