staging: wlan-ng: avoid new typedef: p80211item_pstr255_t

This patch fixes the following checkpatch.pl warning in p80211types.h:
WARNING: do not add new typedefs

It applies for typedef p80211item_pstr255_t
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/p80211types.h

@@ -302,12 +302,12 @@ struct p80211item_pstr32 {
 } __packed;
 
 /* message data item for OCTETSTR, DISPLAYSTR */
-typedef struct p80211item_pstr255 {
+struct p80211item_pstr255 {
 	u32 did;
 	u16 status;
 	u16 len;
 	struct p80211pstr255 data;
-} __packed p80211item_pstr255_t;
+} __packed;
 
 /* message data item for UNK 392, namely mib items */
 typedef struct p80211item_unk392 {