irda: net/irda build fix: mcs7780

-tip testing found the following build error:

  drivers/built-in.o: In function `mcs_receive_irq':
  mcs7780.c:(.text+0x4e429): undefined reference to `crc32_le'
  drivers/built-in.o: In function `mcs_hard_xmit':
  mcs7780.c:(.text+0x4e9af): undefined reference to `crc32_le'

with:

  http://redhat.com/~mingo/misc/config-Sun_Jun__8_22_56_14_CEST_2008.bad

the reason is a missing enablement of the CRC32 library in the Kconfig.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Samuel Ortiz <samuel@sortiz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/irda/Kconfig b/drivers/net/irda/Kconfig
index ce816ba..e631755 100644
--- a/drivers/net/irda/Kconfig
+++ b/drivers/net/irda/Kconfig
@@ -329,6 +329,7 @@
 config MCS_FIR
 	tristate "MosChip MCS7780 IrDA-USB dongle"
 	depends on IRDA && USB && EXPERIMENTAL
+	select CRC32
 	help
 	  Say Y or M here if you want to build support for the MosChip
 	  MCS7780 IrDA-USB bridge device driver.