drivers: net: Remove casts to same type

Adding casts of objects to the same type is unnecessary
and confusing for a human reader.

For example, this cast:

        int y;
        int *p = (int *)&y;

I used the coccinelle script below to find and remove these
unnecessary casts.  I manually removed the conversions this
script produces of casts with __force, __iomem and __user.

@@
type T;
T *p;
@@

-       (T *)p
+       p

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index d4c9db3..a34d6bf 100644
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -390,10 +390,10 @@
 #endif
 #ifdef CONFIG_SLIP_MODE_SLIP6
 	if (sl->mode & SL_MODE_SLIP6)
-		count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
+		count = slip_esc6(p, sl->xbuff, len);
 	else
 #endif
-		count = slip_esc(p, (unsigned char *) sl->xbuff, len);
+		count = slip_esc(p, sl->xbuff, len);
 
 	/* Order of next two lines is *very* important.
 	 * When we are sending a little amount of data,