drivers: char: mem: use IS_ERR_VALUE() in memory_lseek()

Use IS_ERR_VALUE() instead of comparing the new offset to a hard-coded
value of -MAX_ERRNO (which is also off-by-one due to the use of ~
instead of -).
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/mem.c

@@ -745,7 +745,7 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 		offset += file->f_pos;
 	case SEEK_SET:
 		/* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
-		if ((unsigned long long)offset >= ~0xFFFULL) {
+		if (IS_ERR_VALUE((unsigned long long)offset)) {
 			ret = -EOVERFLOW;
 			break;
 		}