Staging: rtl8712: Remove zero-testing pointer typed value

Removes variable comparison with 0 by using !. Done using following
coccinelle script.

@ disable is_zero,isnt_zero @
expression *E;
expression E1,f;
@@

E = f(...)
<...
(
- E == 0
+ !E
|
- E != 0
+ E
|
- 0 == E
+ !E
|
- 0 != E
+ E
)
...>
?E = E1

@ disable is_zero,isnt_zero @
expression *E;
@@

(
  E ==
- 0
+ NULL
|
  E !=
- 0
+ NULL
|
- 0
+ NULL
  == E
|
- 0
+ NULL
  != E
)

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>