irqchip/sg2042-msi: Add missing chip flags

The sg2042-msi driver uses the fallback callbacks set by
msi_lib_init_dev_msi_info(). commit 1c000dca ("irqchip/irq-msi-lib:
Optionally set default irq_eoi()/irq_ack()") changed the behavior of the
fallback mechanism by making it opt-in.

The sg2042-msi was not fixed up for this, which causes a NULL pointer
dereference due to the missing irq_ack() callback.

Add the missing chip flag to msi_parent_ops.

Fixes: c6674154 ("irqchip: Add the Sophgo SG2042 MSI interrupt controller")
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250217085657.789309-3-apatel@ventanamicro.com
Link: https://lore.kernel.org/all/20250405055625.1530180-1-inochiama@gmail.com