Once an interrupt has been claimed, but before it has been compelted we
shouldn't receive any more pending interrupts. This patche keeps track
of this to ensure that we don't see any more interrupts until it is
completed.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <394c3f070615ff2b4fab61a1cf9cb48c122913b7.1595655188.git.alistair.francis@wdc.com>