erofs: fix error handling in z_erofs_init_decompressor

If we get a failure at the first decompressor init (i = 0),
the clean up while loop could enter infinite loop due to wrong while
check. Check the value of i now to see if we need any clean up at all.

Fixes: 5a7cce82 ("erofs: refine z_erofs_{init,exit}_subsystem()")
Reported-by: liujinbao1 <liujinbao1@xiaomi.com>
Signed-off-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20240905060027.2388893-1-dhavale@google.comSigned-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/decompressor.c

@@ -539,7 +539,7 @@ int __init z_erofs_init_decompressor(void)
 	for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) {
 		err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0;
 		if (err) {
-			while (--i)
+			while (i--)
 				if (z_erofs_decomp[i])
 					z_erofs_decomp[i]->exit();
 			return err;