staging/rtl8187se: Fix compile warning 'is static but declared in .. which is not static'

When compiling this driver I get these compile warnings:

ieee80211.h:1227:2: warning: '______f' is static but declared in inline
function 'ieee80211_is_empty_essid' which is not static [enabled by
default]
ieee80211.h:1233:3: warning: '______f' is static but declared in inline
function 'ieee80211_is_empty_essid' which is not static [enabled by
default]
ieee80211.h:1248:2: warning: '______f' is static but declared in inline
function 'ieee80211_is_valid_mode' which is not static [enabled by
default]
ieee80211.h:1253:2: warning: '______f' is static but declared in inline
function 'ieee80211_is_valid_mode' which is not static [enabled by
default]
ieee80211.h:1258:2: warning: '______f' is static but declared in inline
function 'ieee80211_is_valid_mode' which is not static [enabled by
default]
ieee80211.h:1272:3: warning: '______f' is static but declared in inline
function 'ieee80211_get_hdrlen' which is not static [enabled by default]
ieee80211.h:1274:3: warning: '______f' is static but declared in inline
function 'ieee80211_get_hdrlen' which is not static [enabled by default]

These functions are declared as extern inline but not 'overloaded'
anywhere so we can declare them static inline and get rid of the
warnings.
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8187se/ieee80211/ieee80211.h

@@ -1221,7 +1221,7 @@ static inline void *ieee80211_priv(struct net_device *dev)
 	return ((struct ieee80211_device *)netdev_priv(dev))->priv;
 }
 
-extern inline int ieee80211_is_empty_essid(const char *essid, int essid_len)
+static inline int ieee80211_is_empty_essid(const char *essid, int essid_len)
 {
 	/* Single white space is for Linksys APs */
 	if (essid_len == 1 && essid[0] == ' ')
@@ -1237,7 +1237,7 @@ extern inline int ieee80211_is_empty_essid(const char *essid, int essid_len)
 	return 1;
 }
 
-extern inline int ieee80211_is_valid_mode(struct ieee80211_device *ieee, int mode)
+static inline int ieee80211_is_valid_mode(struct ieee80211_device *ieee, int mode)
 {
 	/*
 	 * It is possible for both access points and our device to support
@@ -1263,7 +1263,7 @@ extern inline int ieee80211_is_valid_mode(struct ieee80211_device *ieee, int mod
 	return 0;
 }
 
-extern inline int ieee80211_get_hdrlen(u16 fc)
+static inline int ieee80211_get_hdrlen(u16 fc)
 {
 	int hdrlen = 24;