drivers: staging: rtl8712: Removed unnecessary parentheses

Parentheses around the right side of an assignment statement are
unnecessary and hence removed. Coccinelle was used to produce the
patch:

@rule1@
identifier x,y;
constant c;
@@

(

 x =
-(
 y << c
-)
 ;
|
 x =
-(
 y >> c
-)
 ;
|
 x =
-(
 y + c
-)
 ;
|
 x =
-(
 y - c
-)
 ;

)

Signed-off-by: Tina Johnson <tinajohnson.1234@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>