irda: convert to netdev_tx_t

drivers/net/irda/ali-ircc.c

drivers/net/irda/donauboe.c

drivers/net/irda/irda-usb.c

drivers/net/irda/kingsun-sir.c

drivers/net/irda/ks959-sir.c

drivers/net/irda/ksdazzle-sir.c

drivers/net/irda/mcs7780.c

drivers/net/irda/mcs7780.h

drivers/net/irda/nsc-ircc.c

drivers/net/irda/sir_dev.c

drivers/net/irda/smsc-ircc2.c

drivers/net/irda/stir4200.c

drivers/net/irda/via-ircc.c

drivers/net/irda/vlsi_ir.c

drivers/net/irda/w83977af_ir.c

net/irda/irlan/irlan_eth.c