haven: irq_lend: Lendee registration persists across transactions

Presently, clients must re-register to receive IRQ lend notification.
Every client presently must do this and there is no use-case to require
clients to re-register to receive IRQ lend notification. Return the
internal IRQ lend state to WAIT_LEND after release, instead of
unregistered.

Change-Id: I17504e2850ae60e68d755b587ff6d0c3e78926d9
Signed-off-by: Elliot Berman <eberman@codeaurora.org>