mtd: nand: switch `check_pattern()' to standard `memcmp()'

A portion of the `check_pattern()' function is basically a `memcmp()'.
Since it's possible for `memcmp()' to be optimized for a particular
architecture, we should use it instead.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>

drivers/mtd/nand/nand_bbt.c

@@ -107,10 +107,8 @@ static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_desc
 	p += end;
 
 	/* Compare the pattern */
-	for (i = 0; i < td->len; i++) {
-		if (p[i] != td->pattern[i])
-			return -1;
-	}
+	if (memcmp(p, td->pattern, td->len))
+		return -1;
 
 	if (td->options & NAND_BBT_SCANEMPTY) {
 		p += td->len;