Staging: cpc-usb: Adjust NULL test

Since card must already be non-NULL, it seems that what was intended
was to test the result of kmalloc.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E,E1;
identifier f,fld,fld1;
statement S1,S2;
@@

E->fld = f(...);
... when != E = E1
    when != E->fld1 = E1
if (
-   E
+   E->fld
           == NULL) S1 else S2
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>