mtd: rawnand: mpc5121: Check before clk_disable_unprepare() not needed

All code in clk_disable_unprepare() already checks the clk ptr using
IS_ERR_OR_NULL so there is no need to check it again before calling it.
A lot of other drivers already rely on this behaviour, so it's safe
to do so here.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220512185033.46901-1-phil.edworthy@renesas.com

drivers/mtd/nand/raw/mpc5121_nfc.c

@@ -595,8 +595,7 @@ static void mpc5121_nfc_free(struct device *dev, struct mtd_info *mtd)
 	struct nand_chip *chip = mtd_to_nand(mtd);
 	struct mpc5121_nfc_prv *prv = nand_get_controller_data(chip);
 
-	if (prv->clk)
-		clk_disable_unprepare(prv->clk);
+	clk_disable_unprepare(prv->clk);
 
 	if (prv->csreg)
 		iounmap(prv->csreg);