staging/rtl8187se: Fix spacing coding style in ieee80211/ieee80211_rx.c

The following warnings fixed.
- WARNING: braces {} are not necessary for single statement blocks

Signed-off-by: YAMANE Toshiaki <yamanetoshi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>