qcacmn: Add APIs to get IE by EID and Ext ID

Add wlan utility APIs to get IE pointer from within IE buffer by
EID or Ext ID.

Change-Id: I26492078cec73b5877f3fc346a91223a045f31aa
CRs-Fixed: 2103529
diff --git a/umac/cmn_services/inc/wlan_cmn.h b/umac/cmn_services/inc/wlan_cmn.h
index 9a37679..ca690a8 100644
--- a/umac/cmn_services/inc/wlan_cmn.h
+++ b/umac/cmn_services/inc/wlan_cmn.h
@@ -91,6 +91,7 @@
 #define WLAN_CHAN_170_FREQ      (5852)
 
 #define WLAN_MAC_EID_VENDOR     221
+#define WLAN_MAC_EID_EXT        255
 
 /**
  * enum wlan_umac_comp_id - UMAC component id