staging: rtl8712: Remove unnecessary parentheses

Remove unnecessary parentheses between 'address-of' operators
and struct members.
Issues found with checkpatch.pl

Signed-off-by: Dafna Hirschfeld <dafna3@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>