x25: remove redundant pointer dev

Pointer dev is being assigned a value that is never used, the assignment
and the variable are redundant and can be removed. Also replace null check
with the preferred !ptr idiom.

Cleans up clang scan warning:
net/x25/x25_proc.c:94:26: warning: Although the value stored to 'dev' is
used in the enclosing expression, the value is never actually read
from 'dev' [deadcode.DeadStores]

Signed-off-by: Colin Ian King <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

net/x25/x25_proc.c

···
 {
 	struct sock *s;
 	struct x25_sock *x25;
-	struct net_device *dev;
 	const char *devname;
 
 	if (v == SEQ_START_TOKEN) {
···
 	s = sk_entry(v);
 	x25 = x25_sk(s);
 
-	if (!x25->neighbour || (dev = x25->neighbour->dev) == NULL)
+	if (!x25->neighbour || !x25->neighbour->dev)
 		devname = "???";
 	else
 		devname = x25->neighbour->dev->name;