[SCSI] fcoe, libfc: use single frame allocation API

Cleans up frame allocation APIs to have just single fc_frame_alloc API.

Removes _fc_frame_alloc, renames __fc_frame_alloc to _fc_frame_alloc.

Modifies fc_fcp_send_data for removed _fc_frame_alloc, fc_fcp_send_data
was the only user of removed _fc_frame_alloc.

Also Adds check in fc_frame_alloc to do mod by 4 for only non-zero
len value.

This patch is prep work to fix can_queue reducing in next patch.
Single fc_frame_alloc API helps in fixing can_queue reducing in
next patch.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index 970b54f..567eee7 100644
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -505,18 +505,11 @@
 			 */
 			if (tlen % 4)
 				using_sg = 0;
-			if (using_sg) {
-				fp = _fc_frame_alloc(lport, 0);
-				if (!fp)
-					return -ENOMEM;
-			} else {
-				fp = fc_frame_alloc(lport, tlen);
-				if (!fp)
-					return -ENOMEM;
+			fp = fc_frame_alloc(lport, using_sg ? 0 : tlen);
+			if (!fp)
+				return -ENOMEM;
 
-				data = (void *)(fr_hdr(fp)) +
-					sizeof(struct fc_frame_header);
-			}
+			data = fc_frame_header_get(fp) + 1;
 			fh_parm_offset = frame_offset;
 			fr_max_payload(fp) = fsp->max_payload;
 		}