net: wireless: Remove useless return variables

net: wireless: Remove useless return variables

This patch remove variables that are initialized with a constant,
are never updated, and are only used as parameter of return.
Return the constant instead of using a variable.

wl_cfg80211.c verified by compilation only.
phy/phy_cmn.c unverified.

The coccinelle script that find and fixes this issue is:
// <smpl>
@@
type T;
constant C;
identifier ret;
@@
- T ret = C;
... when != ret
    when strict
return
- ret
+ C
;
// </smpl>

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>