irqchip/imx-irqsteer: Constify irq_chip struct

[ Upstream commit e9a50f12e579a48e124ac5adb93dafc35f0a46b8 ]

The imx_irqsteer_irq_chip struct is constant data.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220406163701.1277930-1-l.stach@pengutronix.de


Stable-dep-of: 33b1c47d1fc0 ("irqchip/imx-irqsteer: Handle runtime power management correctly")
Signed-off-by: Sasha Levin <sashal@kernel.org>