10687 Service routine cast changes need smatch fixes

*** 2,11 ****
--- 2,12 ----
   * sppp.c - Solaris STREAMS PPP multiplexing pseudo-driver
   *
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   * Copyright (c) 2016 by Delphix. All rights reserved.
+  * Copyright 2019, Joyent, Inc.
   *
   * Permission to use, copy, modify, and distribute this software and its
   * documentation is hereby granted, provided that the above copyright
   * notice appears in all copies.
   *
*** 1840,1850 ****
  sppp_lrsrv(queue_t *q)
  {
          mblk_t *mp;
  
          while ((mp = getq(q)) != NULL)
!                 sppp_lrput(q, mp);
          return (0);
  }
  
  /*
   * sppp_recv_nondata()
--- 1841,1851 ----
  sppp_lrsrv(queue_t *q)
  {
          mblk_t *mp;
  
          while ((mp = getq(q)) != NULL)
!                 (void) sppp_lrput(q, mp);
          return (0);
  }
  
  /*
   * sppp_recv_nondata()