mtd: rawnand: remove unused is_imx51_nfc and imx53_nfc functions

clang with W=1 reports
drivers/mtd/nand/raw/mxc_nand.c:1602:19: error: unused function
  'is_imx51_nfc' [-Werror,-Wunused-function]
static inline int is_imx51_nfc(struct mxc_nand_host *host)
                  ^
drivers/mtd/nand/raw/mxc_nand.c:1607:19: error: unused function
  'is_imx53_nfc' [-Werror,-Wunused-function]
static inline int is_imx53_nfc(struct mxc_nand_host *host)
                  ^
These functions are not used, so remove them.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230321114638.1782086-1-trix@redhat.com

Author: Tom Rix

drivers/mtd/nand/raw/mxc_nand.c

@@ -1599,16 +1599,6 @@ static inline int is_imx25_nfc(struct mxc_nand_host *host)
 	return host->devtype_data == &imx25_nand_devtype_data;
 }
 
-static inline int is_imx51_nfc(struct mxc_nand_host *host)
-{
-	return host->devtype_data == &imx51_nand_devtype_data;
-}
-
-static inline int is_imx53_nfc(struct mxc_nand_host *host)
-{
-	return host->devtype_data == &imx53_nand_devtype_data;
-}
-
 static const struct of_device_id mxcnd_dt_ids[] = {
 	{ .compatible = "fsl,imx21-nand", .data = &imx21_nand_devtype_data, },
 	{ .compatible = "fsl,imx27-nand", .data = &imx27_nand_devtype_data, },