net/irda: convert au1k_ir to platform driver.

Moderate driver cleanup:
convert to platform driver, get rid of board-specific code.

Driver loads and runs on a DB1100 board.  But since I have no other
IrDA hardware to exchange data with I can't say whether it really sends
and receives.

Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: netdev@vger.kernel.org
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2877/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/drivers/net/irda/Kconfig b/drivers/net/irda/Kconfig
index d423d18..e535137 100644
--- a/drivers/net/irda/Kconfig
+++ b/drivers/net/irda/Kconfig
@@ -313,8 +313,12 @@
 	  donauboe.
 
 config AU1000_FIR
-	tristate "Alchemy Au1000 SIR/FIR"
+	tristate "Alchemy IrDA SIR/FIR"
 	depends on IRDA && MIPS_ALCHEMY
+	help
+	  Say Y/M here to build suppor the the IrDA peripheral on the
+	  Alchemy Au1000 and Au1100 SoCs.
+	  Say M to build a module; it will be called au1k_ir.ko
 
 config SMC_IRCC_FIR
 	tristate "SMSC IrCC (EXPERIMENTAL)"