drm/xe: Fix circular locking dependency

drm/xe: Fix circular locking dependency

Fix this:

 ======================================================
 WARNING: possible circular locking dependency detected
 6.17.0-rc4-lgci-xe-xe-pw-153723v2+ #1 Tainted: G S   U
 ------------------------------------------------------
 xe_pm/11324 is trying to acquire lock:
 ffff8881085f22a0 (&pc->freq_lock){+.+.}-{3:3}, at:
 		  xe_guc_pc_start+0x39f/0xf70 [xe]

but task is already holding lock:

 ffffffffa1020420 (xe_rpm_nod3cold_map){+.+.}-{0:0}, at:
 		  xe_rpm_lockmap_acquire+0x1a/0x70 [xe]

which lock already depends on the new lock.

Possible unsafe locking scenario:
      CPU0                    CPU1
      ----                    ----
 lock(xe_rpm_nod3cold_map);
                              lock(&pc->freq_lock);
                              lock(xe_rpm_nod3cold_map);
 lock(&pc->freq_lock);

Reported-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6122
Fixes: 60d2b7899142 ("drm/xe/guc: Add SLPC power profile interface")
Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Tested-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://lore.kernel.org/r/20250911212024.966757-2-rodrigo.vivi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>