drivers/net: Remove redundant test

In each case, ap is checked not to be NULL a few lines before.

A simplified version of the semantic patch that makes this change is as
follows: (http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r exists@
local idexpression x;
expression E;
position p1,p2;
@@

if (x@p1 == NULL || ...) { ... when forall
   return ...; }
... when != \(x=E\|x--\|x++\|--x\|++x\|x-=E\|x+=E\|x|=E\|x&=E\|&x\)
(
x@p2 == NULL
|
x@p2 != NULL
)

// another path to the test that is not through p1?
@s exists@
local idexpression r.x;
position r.p1,r.p2;
@@

... when != x@p1
(
x@p2 == NULL
|
x@p2 != NULL
)

@fix depends on !s@
position r.p1,r.p2;
expression x,E;
statement S1,S2;
@@

(
- if ((x@p2 != NULL) || ...)
  S1
|
- if ((x@p2 == NULL) && ...) S1
|
- BUG_ON(x@p2 == NULL);
)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ppp_async.c

@@ -293,9 +293,6 @@ ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
 	err = -EFAULT;
 	switch (cmd) {
 	case PPPIOCGCHAN:
-		err = -ENXIO;
-		if (!ap)
-			break;
 		err = -EFAULT;
 		if (put_user(ppp_channel_index(&ap->chan), p))
 			break;
@@ -303,9 +300,6 @@ ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
 		break;
 
 	case PPPIOCGUNIT:
-		err = -ENXIO;
-		if (!ap)
-			break;
 		err = -EFAULT;
 		if (put_user(ppp_unit_number(&ap->chan), p))
 			break;

drivers/net/ppp_synctty.c

@@ -333,9 +333,6 @@ ppp_synctty_ioctl(struct tty_struct *tty, struct file *file,
 	err = -EFAULT;
 	switch (cmd) {
 	case PPPIOCGCHAN:
-		err = -ENXIO;
-		if (!ap)
-			break;
 		err = -EFAULT;
 		if (put_user(ppp_channel_index(&ap->chan), p))
 			break;
@@ -343,9 +340,6 @@ ppp_synctty_ioctl(struct tty_struct *tty, struct file *file,
 		break;
 
 	case PPPIOCGUNIT:
-		err = -ENXIO;
-		if (!ap)
-			break;
 		err = -EFAULT;
 		if (put_user(ppp_unit_number(&ap->chan), p))
 			break;