wlan: fix compilation errors for PNO and ROAM_SCAN_OFFLOAD feature flags

WLAN driver fails to compile once FEATURE_WLAN_SCAN_PNO and
FEATURE_ROAM_SCAN_OFFLOAD are disabled in KBUILD.

Patch takescare of reported build failures when either or both of
features are disabled.

Change-Id: Iaaf9653653ca5e0c1805c2a97709b68f8b90a699
CRs-Fixed: 572897
diff --git a/CORE/SME/inc/csrInternal.h b/CORE/SME/inc/csrInternal.h
index 080de36..53da1d7 100644
--- a/CORE/SME/inc/csrInternal.h
+++ b/CORE/SME/inc/csrInternal.h
@@ -1367,8 +1367,11 @@
 void csrSetOppositeBandChannelInfo( tpAniSirGlobal pMac );
 void csrConstructCurrentValidChannelList( tpAniSirGlobal pMac, tDblLinkList *pChannelSetList,
                                             tANI_U8 *pChannelList, tANI_U8 bSize, tANI_U8 *pNumChannels );
+
+#ifdef FEATURE_WLAN_SCAN_PNO
 eHalStatus csrScanSavePreferredNetworkFound(tpAniSirGlobal pMac,
             tSirPrefNetworkFoundInd *pPrefNetworkFoundInd);
+#endif //FEATURE_WLAN_SCAN_PNO
 #endif
 
 #ifdef WLAN_FEATURE_VOWIFI_11R