mtd: nand: fix misspelling in ONFI parameter field name

s/strenght/strength/

This field isn't used anywhere, so this rename is safe.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

include/linux/mtd/nand.h

@@ -279,7 +279,7 @@ struct nand_onfi_params {
 	__le16 io_pin_capacitance_typ;
 	__le16 input_pin_capacitance_typ;
 	u8 input_pin_capacitance_max;
-	u8 driver_strenght_support;
+	u8 driver_strength_support;
 	__le16 t_int_r;
 	__le16 t_ald;
 	u8 reserved4[7];