net: wwan: iosm: fix kernel test robot reported error

sparse warnings - iosm_ipc_mux_codec.c:1474 using plain
integer as NULL pointer.

Use skb_trim() to reset skb tail & len.

Fixes: 9413491e20 ("net: iosm: encode or decode datagram")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
M Chetan Kumar 2022-11-24 16:07:46 +05:30 • committed by David S. Miller
commit 985a02e758