irqchip/gic-v3-its: Reference to its_invall_cmd descriptor when building INVALL

It looks like an obvious mistake to use its_mapc_cmd descriptor when
building the INVALL command block. It so far worked by luck because
both its_mapc_cmd.col and its_invall_cmd.col sit at the same offset of
the ITS command descriptor, but we should not rely on it.

Fixes: cc2d3216 ("irqchip: GICv3: ITS command queue")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191202071021.1251-1-yuzenghui@huawei.com

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

@@ -661,7 +661,7 @@ static struct its_collection *its_build_invall_cmd(struct its_node *its,
 						   struct its_cmd_desc *desc)
 {
 	its_encode_cmd(cmd, GITS_CMD_INVALL);
-	its_encode_collection(cmd, desc->its_mapc_cmd.col->col_id);
+	its_encode_collection(cmd, desc->its_invall_cmd.col->col_id);
 
 	its_fixup_cmd(cmd);