[codex] Fix IAR file lock mutex bounds

[Old-Ding]

Summary

• update IAR file lock mutex allocation bounds to use _MAX_FLOCK
• keep system lock allocation bounds on _MAX_LOCK
• apply the same fix across the duplicated IAR ThreadX port sources

Root cause

The file lock mutex pool is sized with _MAX_FLOCK, but its round-robin allocation checks used _MAX_LOCK in two places. When _MAX_FLOCK is larger than _MAX_LOCK, the allocator can wrap or report exhaustion using the system-lock limit instead of the file-lock pool size.

Validation

• git diff --check
• verified all 26 changed files only replace the file-lock wrap/no-free checks from _MAX_LOCK to _MAX_FLOCK
• verified no remaining file_lock references use _MAX_LOCK