staging: rtl8192u: fix incorrect assignments

Fixing warnings found by sparse on rtl8192u/ieee80211.

drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1318:45: warning: incorrect type in assignment (different base types)
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1318:45:    expected unsigned short [unsigned] [usertype] len
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1318:45:    got restricted __be16 [usertype] <noident>

drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1481:40: warning: incorrect type in assignment (different base types)
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1481:40:    expected restricted __le16 <noident>
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1481:40:    got int

drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1483:40: warning: incorrect type in assignment (different base types)
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1483:40:    expected restricted __le16 <noident>
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1483:40:    got int

drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1487:45: warning: incorrect type in assignment (different base types)
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1487:45:    expected restricted __le16 <noident>
drivers/staging/rtl8192u/ieee80211//ieee80211_rx.c:1487:45:    gotunsigned short [unsigned] [usertype] <noident>

Signed-off-by: Jakub Jedelsky <jakub.jedelsky@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>