erofs: don't trigger WARN() when decompression fails

syzbot reported a WARNING [1] due to corrupted compressed data.

As Dmitry said, "If this is not a kernel bug, then the code should
not use WARN. WARN if for kernel bugs and is recognized as such by
all testing systems and humans."

[1] https://lore.kernel.org/r/[email protected]

Link: https://lore.kernel.org/r/[email protected]
Cc: Dmitry Vyukov <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Reported-by: [email protected]
Signed-off-by: Gao Xiang <[email protected]>

Author: hsiangkao

fs/erofs/decompressor.c

@@ -227,7 +227,6 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
 		erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 			  ret, rq->inputsize, inputmargin, rq->outputsize);
 
-		WARN_ON(1);
 		print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
 			       16, 1, src + inputmargin, rq->inputsize, true);
 		print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,