irqchip/gic-v3-its: Move minimum LPI requirements to individual busses

At the moment, the core ITS driver imposes the allocation to be
in chunks of 32. As we want to relax this on a per bus basis, let's
move the the the allocation constraints to each bus.

No functionnal change.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-v3-its-platform-msi.c

@@ -73,6 +73,8 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 	/* ITS specific DeviceID, as the core ITS ignores dev. */
 	info->scratchpad[0].ul = dev_id;
 
+	/* Allocate at least 32 MSIs, and always as a power of 2 */
+	nvec = max_t(int, 32, roundup_pow_of_two(nvec));
 	return msi_info->ops->msi_prepare(domain->parent,
 					  dev, nvec, info);
 }