intel: add cmd_fail() to signal command buffer errors

The main purpose is have a place to set breakpoing on on command buffer
errors.
diff --git a/icd/intel/cmd_mi.c b/icd/intel/cmd_mi.c
index 529503a..6a8d8a3 100644
--- a/icd/intel/cmd_mi.c
+++ b/icd/intel/cmd_mi.c
@@ -140,7 +140,7 @@
         cmd_query_pipeline_statistics(cmd, bo, offset);
         break;
     default:
-        cmd->result = XGL_ERROR_UNKNOWN;
+        cmd_fail(cmd, XGL_ERROR_UNKNOWN);
         break;
     }
 }
@@ -164,7 +164,7 @@
                 offset + sizeof(XGL_PIPELINE_STATISTICS_DATA));
         break;
     default:
-        cmd->result = XGL_ERROR_UNKNOWN;
+        cmd_fail(cmd, XGL_ERROR_UNKNOWN);
         break;
     }
 }
@@ -205,7 +205,7 @@
         pipe_control_flags = GEN6_PIPE_CONTROL_CS_STALL;
         break;
     default:
-        cmd->result = XGL_ERROR_UNKNOWN;
+        cmd_fail(cmd, XGL_ERROR_UNKNOWN);
         return;
         break;
     }
@@ -246,7 +246,7 @@
         cmd_batch_timestamp(cmd, buf->obj.mem->bo, destOffset);
         break;
     default:
-        cmd->result = XGL_ERROR_INVALID_VALUE;
+        cmd_fail(cmd, XGL_ERROR_INVALID_VALUE);
         break;
     }
 }