drivers/isdn/hardware/icon: fix sparse warning: cast truncates bits

Fix this sparse warning:
  drivers/isdn/hardware/eicon/debug.c:1201:32: warning: cast truncates bits from constant value (1000 becomes 0)
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hardware/eicon/debug.c

@@ -1198,7 +1198,7 @@ int SuperTraceASSIGN (void* AdapterHandle, byte* data) {
         pC->xbuffer[5] = (byte)(rx_dma_magic >>  8);
         pC->xbuffer[6] = (byte)(rx_dma_magic >> 16);
         pC->xbuffer[7] = (byte)(rx_dma_magic >> 24);
-        pC->xbuffer[8] = (byte)DIVA_MAX_MANAGEMENT_TRANSFER_SIZE;
+	pC->xbuffer[8] = (byte)(DIVA_MAX_MANAGEMENT_TRANSFER_SIZE & 0xFF);
         pC->xbuffer[9] = (byte)(DIVA_MAX_MANAGEMENT_TRANSFER_SIZE >> 8);
         pC->xbuffer[10] = 0;