haven: rm: Allow IRQ lender to learn about the IRQ handle

An IRQ lender driver will likely ought to need to use the IRQ handle to
reclaim the interrupt when the lendee is done with the interrupt.

Change-Id: I0b791ecfb7b169d5cf2677d324e9aceea51feb5d
Signed-off-by: Elliot Berman <eberman@codeaurora.org>