drm/i915/guc: Stop using mutex while sending CTB messages

We are no longer using descriptor to hold G2H replies and we are
protecting access to the descriptor and command buffer by the
separate spinlock, so we can stop using mutex.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210603051630.2635-17-matthew.brost@intel.com

Author: mwajdecz

drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c

@@ -559,7 +559,6 @@ static int ct_send(struct intel_guc_ct *ct,
 int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len,
 		      u32 *response_buf, u32 response_buf_size)
 {
-	struct intel_guc *guc = ct_to_guc(ct);
 	u32 status = ~0; /* undefined */
 	int ret;
 
@@ -568,8 +567,6 @@ int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len,
 		return -ENODEV;
 	}
 
-	mutex_lock(&guc->send_mutex);
-
 	ret = ct_send(ct, action, len, response_buf, response_buf_size, &status);
 	if (unlikely(ret < 0)) {
 		CT_ERROR(ct, "Sending action %#x failed (err=%d status=%#X)\n",
@@ -579,7 +576,6 @@ int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len,
 			 action[0], ret, ret);
 	}
 
-	mutex_unlock(&guc->send_mutex);
 	return ret;
 }