staging: wlan-ng: remove unused function prototypes

These functions are declared but not defined or used anywhere. Their
definitions were removed 15 years ago.

prism2mgmt_set_grpaddr() was removed in the
commit 1e720183 ("Staging: wlan-ng: Delete a pile of unused mibs.
And fix WEXT SET_TXPOWER.")
It's signature was changed in the commit 5a2214e2 ("staging:
wlang-ng: avoid new typedef: hfa384x_t")

prism2mgmt_get_grpaddr() and prism2mgmt_get_grpaddr_index() were
removed in the commit cbec30c4 ("Staging: wlan-ng: Delete a large pile of
now-unused code.")
Signed-off-by: Calvince Otieno <calvncce@gmail.com>
Link: https://lore.kernel.org/r/ZSxFS8EnFr998PqS@lab-ubuntuSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/prism2mgmt.h

@@ -78,14 +78,6 @@ void prism2mgmt_pstr2bytestr(struct hfa384x_bytestr *bytestr,
 void prism2mgmt_bytestr2pstr(struct hfa384x_bytestr *bytestr,
 			     struct p80211pstrd *pstr);
 
-/* functions to convert Group Addresses */
-void prism2mgmt_get_grpaddr(u32 did, struct p80211pstrd *pstr,
-			    struct hfa384x *priv);
-int prism2mgmt_set_grpaddr(u32 did,
-			   u8 *prism2buf, struct p80211pstrd *pstr,
-			   struct hfa384x *priv);
-int prism2mgmt_get_grpaddr_index(u32 did);
-
 void prism2sta_processing_defer(struct work_struct *data);
 
 void prism2sta_commsqual_defer(struct work_struct *data);