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: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/hardware/eicon/debug.c b/drivers/isdn/hardware/eicon/debug.c
index 84318ec..33ce89e 100644
--- a/drivers/isdn/hardware/eicon/debug.c
+++ b/drivers/isdn/hardware/eicon/debug.c
@@ -1198,7 +1198,7 @@
         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;