staging: rtl8192u: sparse warnings: declare ieee80211_TURBO_Info static

Declare ieee80211_TURBO_Info static to fix a sparse "symbol was not declared" warning.
Signed-off-by: Merlin Chlosta <eudyptula@merlin.geekmail.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/ieee80211/ieee80211_softmac.c

@@ -124,7 +124,8 @@ static void ieee80211_WMM_Info(struct ieee80211_device *ieee, u8 **tag_p)
 }
 
 #ifdef THOMAS_TURBO
-void ieee80211_TURBO_Info(struct ieee80211_device *ieee, u8 **tag_p) {
+static void ieee80211_TURBO_Info(struct ieee80211_device *ieee, u8 **tag_p)
+{
 	u8 *tag = *tag_p;
 
 	*tag++ = MFIE_TYPE_GENERIC; //0