f2fs: fix to avoid potential panic during recovery

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid potential panic during recovery During recovery, if FAULT_BLOCK is on, it is possible that f2fs_reserve_new_block() will return -ENOSPC during recovery, then it may trigger panic. Also, if fault injection rate is 1 and only FAULT_BLOCK fault type is on, it may encounter deadloop in loop of block reservation. Let's change as below to fix these issues: - remove bug_on() to avoid panic. - limit the loop count of block reservation to avoid potential deadloop.