drm/xe/guc: Prevent use of uninitialized mutex

When skip_guc_pc is set and/or this is for a VF.

Fixes: 3b1592fb78 ("drm/xe/lnl: Apply Wa_22019338487")
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240701231529.2582452-1-vinay.belgaumkar@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_guc_pc.c

@@ -26,6 +26,7 @@
 #include "xe_mmio.h"
 #include "xe_pcode.h"
 #include "xe_pm.h"
+#include "xe_sriov.h"
 #include "xe_wa.h"
 
 #define MCHBAR_MIRROR_BASE_SNB	0x140000
@@ -825,6 +826,9 @@ int xe_guc_pc_restore_stashed_freq(struct xe_guc_pc *pc)
 {
 	int ret = 0;
 
+	if (IS_SRIOV_VF(pc_to_xe(pc)) || pc_to_xe(pc)->info.skip_guc_pc)
+		return 0;
+
 	mutex_lock(&pc->freq_lock);
 	ret = pc_set_max_freq(pc, pc->stashed_max_freq);
 	if (!ret)