ice: Suppress false-positive style issues reported by static analyzer

A recent version of cppcheck falsely reports-
    Variable ip.hdr is assigned a value that is never used.

ip is a union so the pointer ip.hdr is actually used when referenced as
ip.v4 and ip.v6.  Silence these false reports when using cppcheck with the
--inline-suppr command-line option.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -1849,6 +1849,7 @@ int ice_tso(struct ice_tx_buf *first, struct ice_tx_offload_params *off)
 	if (err < 0)
 		return err;
 
+	/* cppcheck-suppress unreadVariable */
 	ip.hdr = skb_network_header(skb);
 	l4.hdr = skb_transport_header(skb);