staging: vt6655: Fix RFbSetPower() error: buffer overflow 'priv->abyCCKPwrTbl' 15 <= 56

Check uCH is not more than CB_MAX_CHANNEL_24G(14) on rates RATE_1M to RATE_11M

Return false as the call is invalid as these rates do not exist
above channel 14.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6655/rf.c

@@ -788,6 +788,9 @@ bool RFbSetPower(
 	case RATE_2M:
 	case RATE_5M:
 	case RATE_11M:
+		if (uCH > CB_MAX_CHANNEL_24G)
+			return false;
+
 		byPwr = priv->abyCCKPwrTbl[uCH];
 		byPwrdBm = priv->abyCCKDefaultPwr[uCH];
 		break;