mtd: nand: gpmi: replace _manual_ swap with swap macro

Make use of the swap macro and remove unnecessary variables swap.
This makes the code easier to read and maintain.

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Han Xu <han.xu@nxp.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/gpmi-nand/gpmi-nand.c

@@ -1487,12 +1487,8 @@ static int gpmi_ecc_read_page_raw(struct mtd_info *mtd,
 	 * See the layout description for a detailed explanation on why this
 	 * is needed.
 	 */
-	if (this->swap_block_mark) {
-		u8 swap = tmp_buf[0];
-
-		tmp_buf[0] = tmp_buf[mtd->writesize];
-		tmp_buf[mtd->writesize] = swap;
-	}
+	if (this->swap_block_mark)
+		swap(tmp_buf[0], tmp_buf[mtd->writesize]);
 
 	/*
 	 * Copy the metadata section into the oob buffer (this section is
@@ -1615,12 +1611,8 @@ static int gpmi_ecc_write_page_raw(struct mtd_info *mtd,
 	 * See the layout description for a detailed explanation on why this
 	 * is needed.
 	 */
-	if (this->swap_block_mark) {
-		u8 swap = tmp_buf[0];
-
-		tmp_buf[0] = tmp_buf[mtd->writesize];
-		tmp_buf[mtd->writesize] = swap;
-	}
+	if (this->swap_block_mark)
+		swap(tmp_buf[0], tmp_buf[mtd->writesize]);
 
 	chip->write_buf(mtd, tmp_buf, mtd->writesize + mtd->oobsize);