erofs: use wrapper i_blocksize() in erofs_file_read_iter()

[Yangtao Li]

> @@ -380,7 +380,7 @@ static ssize_t erofs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> 		if (bdev)
> 			blksize_mask = bdev_logical_block_size(bdev) - 1;
> 		else
> -			blksize_mask = (1 << inode->i_blkbits) - 1;
> +			blksize_mask = i_blocksize(inode) - 1;

Since the mask is to be obtained here, is it more appropriate to use GENMASK(inode->i_blkbits - 1, 0)?

Thx,
Yangtao