Staging: rtl8187se: Remove unnecessary return statement in ieee80211_crypt_tkip.c

This patch removes an unnecessary return statement in the function
ieee80211_tkip_null() in ieee80211/ieee80211_crypt_tkip.c.

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>