[SCSI] lpfc: convert to use the data buffer accessors

 This patch is a reworked version of the data buffer accessors patch
 so that it applies on the NPIV sources.

 The original patch was developed and submitted by Fujita Tomonori:
      FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
      http://marc.info/?l=linux-scsi&m=117896446832171&w=2



  - remove the unnecessary map_single path.

  - convert to use the new accessors for the sg lists and the
    parameters.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>