irqchip/gic-v3-its: Rely on genpool alignment

JIRA: https://issues.redhat.com/browse/RHEL-62922

commit e36d416
Author: Steven Price <steven.price@arm.com>
Date: Wed, 2 Oct 2024 15:16:30 +0100

    its_create_device() over-allocated by ITS_ITT_ALIGN - 1 bytes to ensure
    that an aligned area was available within the allocation. The new genpool
    allocator has its min_alloc_order set to get_order(ITS_ITT_ALIGN) so all
    allocations from it should be appropriately aligned.

    Remove the over-allocation from its_create_device() and alignment from
    its_build_mapd_cmd().

    Signed-off-by: Steven Price <steven.price@arm.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Tested-by: Will Deacon <will@kernel.org>
    Reviewed-by: Marc Zyngier <maz@kernel.org>
    Link: https://lore.kernel.org/all/20241002141630.433502-3-steven.price@arm.com

Signed-off-by: Charles Mirabile <cmirabil@redhat.com>

Author: Charles Mirabile

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

@@ -705,7 +705,6 @@ static struct its_collection *its_build_mapd_cmd(struct its_node *its,
 	u8 size = ilog2(desc->its_mapd_cmd.dev->nr_ites);
 
 	itt_addr = virt_to_phys(desc->its_mapd_cmd.dev->itt);
-	itt_addr = ALIGN(itt_addr, ITS_ITT_ALIGN);
 
 	its_encode_cmd(cmd, GITS_CMD_MAPD);
 	its_encode_devid(cmd, desc->its_mapd_cmd.dev->device_id);
@@ -3487,7 +3486,7 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 	 */
 	nr_ites = max(2, nvecs);
 	sz = nr_ites * (FIELD_GET(GITS_TYPER_ITT_ENTRY_SIZE, its->typer) + 1);
-	sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
+	sz = max(sz, ITS_ITT_ALIGN);
 
 	itt = itt_alloc_pool(its->numa_node, sz);