mtd: nand: jz4740: remove custom 'erased check' implementation

The jz4740 driver is manually checking for 'erased pages' while
correcting ECC bytes.
This logic can now done by the core infrastructure, and can thus be removed
from this driver.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/jz4740_nand.c

@@ -224,24 +224,6 @@ static int jz_nand_correct_ecc_rs(struct mtd_info *mtd, uint8_t *dat,
 	uint32_t t;
 	unsigned int timeout = 1000;
 
-	t = read_ecc[0];
-
-	if (t == 0xff) {
-		for (i = 1; i < 9; ++i)
-			t &= read_ecc[i];
-
-		t &= dat[0];
-		t &= dat[nand->chip.ecc.size / 2];
-		t &= dat[nand->chip.ecc.size - 1];
-
-		if (t == 0xff) {
-			for (i = 1; i < nand->chip.ecc.size - 1; ++i)
-				t &= dat[i];
-			if (t == 0xff)
-				return 0;
-		}
-	}
-
 	for (i = 0; i < 9; ++i)
 		writeb(read_ecc[i], nand->base + JZ_REG_NAND_PAR0 + i);
 
@@ -443,6 +425,7 @@ static int jz_nand_probe(struct platform_device *pdev)
 	chip->ecc.size		= 512;
 	chip->ecc.bytes		= 9;
 	chip->ecc.strength	= 4;
+	chip->ecc.options	= NAND_ECC_GENERIC_ERASED_CHECK;
 
 	if (pdata)
 		chip->ecc.layout = pdata->ecc_layout;