xirc2ps_cs: remove redundant assignment to variable okay, clean up freespace

The variable okay is being initialized with a value that is never
read, it is being re-assigned later on. The initialization is
redundant and can be removed.  Also clean up assignment to
variable freespace using an assignment and mask operation.

Cleans up clang scan build warning:
drivers/net/ethernet/xircom/xirc2ps_cs.c:1244:5: warning: Value stored
to 'okay' is never read [deadcode.DeadStores]
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240205213643.1850420-1-colin.i.king@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/xircom/xirc2ps_cs.c

@@ -1240,9 +1240,7 @@ do_start_xmit(struct sk_buff *skb, struct net_device *dev)
     netif_stop_queue(dev);
     SelectPage(0);
     PutWord(XIRCREG0_TRS, (u_short)pktlen+2);
-    freespace = GetWord(XIRCREG0_TSO);
-    okay = freespace & 0x8000;
-    freespace &= 0x7fff;
+    freespace = GetWord(XIRCREG0_TSO) & 0x7fff;
     /* TRS doesn't work - (indeed it is eliminated with sil-rev 1) */
     okay = pktlen +2 < freespace;
     pr_debug("%s: avail. tx space=%u%s\n",