wifi: mt76: mt7925: add lockdep assertions for mutex verification

[zbowling]

Add lockdep_assert_held() calls to critical MCU functions to help catch mutex violations during development and debugging. This follows the pattern used in other mt76 drivers (mt7996, mt7915, mt7615).

Functions with new assertions

• mt7925_mcu_add_bss_info(): Core BSS configuration MCU command
• mt7925_mcu_sta_update(): Station record update MCU command
• mt7925_mcu_uni_bss_ps(): Power save state MCU command

Purpose

These functions modify firmware state and must be called with the device mutex held to prevent race conditions. The lockdep assertions will:

1. Help catch mutex violations during development with CONFIG_LOCKDEP=y
2. Document the locking requirements for these functions
3. Make debugging easier when new callers are added

Background

This is a follow-up to my mutex protection patches (PRs #1029, #1030, #1031, #1032, #1033, #1034) and helps ensure the locking requirements are properly enforced.

Related PRs:

• mt7925: fix NULL pointer dereference in vif iteration loops #1027 (MT7925 mutex fixes)
• wifi: mt76: mt7925: add NULL pointer checks in MLO paths #1030-wifi: mt76: mt792x: fix NULL pointer dereference in TX path #1033 (MT7925 NULL checks and error handling)
• wifi: mt76: mt7921: fix missing mutex protection in multiple paths #1034 (MT7921 mutex fixes)

Signed-off-by: Zac Bowling zac@zacbowling.com