irqchip/gic-v3-its: Fix LPI release for Multi-MSI devices

When allocating a range of LPIs for a Multi-MSI capable device,
this allocation extended to the closest power of 2.

But on the release path, the interrupts are released one by
one. This results in not releasing the "extra" range, leaking
the its_device. Trying to reprobe the device will then fail.

Fix it by releasing the LPIs the same way we allocate them.

Fixes: 8208d170

 ("irqchip/gic-v3-its: Align PCI Multi-MSI allocation on their size")
Reported-by: Jiaxing Luo <luojiaxing@huawei.com>
Tested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/f5e948aa-e32f-3f74-ae30-31fee06c2a74@huawei.com