UIO: generic irq handling for some uio platform devices

This is V3 of uio_pdrv_genirq.c, a platform driver for UIO with
generic IRQ handling code. This driver is very similar to the regular
UIO platform driver, but is only suitable for devices that are
connected to the interrupt controller using unique interrupt lines.

The uio_pdrv_genirq driver includes generic interrupt handling code
which disables the serviced interrupt in the interrupt controller
and makes the user space driver responsible for acknowledging the
interrupt in the device and reenabling the interrupt in the interrupt
controller.

Shared interrupts are not supported since the in-kernel interrupt
handler will disable the interrupt line in the interrupt controller,
and in a shared interrupt configuration this will stop other devices
from delivering interrupts.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>