staging: rtl8723au: hal: Remove useless return variables

staging: rtl8723au: hal: Remove useless return variables

This patch removes unnecessary return variables and compresses the
return logic.
The coccinelle script that finds and fixes this issue is:
@@ type T; identifier i,f; constant C; @@
- T i;
...when != i
when strict
( return -C;
|
- i =
+ return
f(...);
- return i;
)

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>