Export IACK status via vme_status

This allows us to check (in polling mode) if an IACK has
been received or not.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
IRQ generation: Ensure that we are not waiting for multiple IACKs

The tsi148 can not distinguish from the IACK which interrupt was
acknowledged. Consequently, if we generate a second interrupt while
the first one has not yet been acknowledged, we will consequently
not know which one was acknowledged once an IACK arrives.
We therefore need to ensure that at most one interrupt acknowledgement
is being waited for.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Interrupt generation: Add possibility to skip waiting for IACK

Allow the user to specify negative timeouts, which instruct the
driver to not wait for an IACK when an interrupt is generated.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
vme: Export autoid from cbar to userland

As per the Siemens convention, the statid is written
to bits 7:3 of cbar after the Monarch's Auto-ID cycle
is finished. Export this value to userland via
VME_GET_STATUS.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>