mwifiex: Remove unused 'chan_num' variable

Commit b5413e6b removed all uses of chan_num in mwifiex_config_scan().
Compiling mwifiex with W=1 gives the following warning, fix it.

mwifiex/scan.c: In function ‘mwifiex_config_scan’:
mwifiex/scan.c:830:6: warning: variable ‘chan_num’ set but not used [-Wunused-but-set-variable]

Fixes: b5413e6b ("mwifiex: increase the number of nodes in command pool")
Cc: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kirtika Ruchandani <kirtika@google.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/scan.c

@@ -827,7 +827,6 @@ mwifiex_config_scan(struct mwifiex_private *priv,
 	u32 num_probes;
 	u32 ssid_len;
 	u32 chan_idx;
-	u32 chan_num;
 	u32 scan_type;
 	u16 scan_dur;
 	u8 channel;
@@ -1105,13 +1104,12 @@ mwifiex_config_scan(struct mwifiex_private *priv,
 			mwifiex_dbg(adapter, INFO,
 				    "info: Scan: Scanning current channel only\n");
 		}
-		chan_num = chan_idx;
 	} else {
 		mwifiex_dbg(adapter, INFO,
 			    "info: Scan: Creating full region channel list\n");
-		chan_num = mwifiex_scan_create_channel_list(priv, user_scan_in,
-							    scan_chan_list,
-							    *filtered_scan);
+		mwifiex_scan_create_channel_list(priv, user_scan_in,
+						 scan_chan_list,
+						 *filtered_scan);
 	}
 
 }