staging: rtl8192u: Remove typedef for struct.

Challenge suggested by coccinelle.

Linux kernel coding style guidelines suggest not using typedefs for
structure.
The following Coccinelle semantic patch detects the cases for struct
type:

@tn@
identifier i;
type td;
@@

-typedef
 struct i { ... }
-td
 ;

@@
type tn.td;
identifier tn.i;
@@

-td
+ struct i

Signed-off-by: Sanjana Sanikommu <sanjana99reddy99@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>