Staging:rtl8192:ieee80211: Fix sparse warning cast to restricted __le32

This patch fixes the following sparse warnings in ieee80211_rx.c:
drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c:2201:34: warning: cast
to restricted __le32
drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c:2202:34: warning: cast
to restricted __le32
drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c:2203:36: warning: cast
to restricted __le32

by changing the annotation in the structure header file for struct
ieee80211_probe_response for time_stamp and altering the cast
for beacon_interval to le16.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Reviewed-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>