irqchip/imx-irqsteer: Handle runtime power management correctly

In the Linux kernel, the following vulnerability has been resolved:

irqchip/imx-irqsteer: Handle runtime power management correctly

The power domain is automatically activated from clk_prepare(). However, on

certain platforms like i.MX8QM and i.MX8QXP, the power-on handling invokes

sleeping functions, which triggers the 'scheduling while atomic' bug in the

context switch path during device probing:

BUG: scheduling while atomic: kworker/u13:1/48/0x00000002

Call trace:

__schedule_bug+0x54/0x6c

__schedule+0x7f0/0xa94

schedule+0x5c/0xc4

schedule_preempt_disabled+0x24/0x40

__mutex_lock.constprop.0+0x2c0/0x540

__mutex_lock_slowpath+0x14/0x20

mutex_lock+0x48/0x54

clk_prepare_lock+0x44/0xa0

clk_prepare+0x20/0x44

imx_irqsteer_resume+0x28/0xe0

pm_generic_runtime_resume+0x2c/0x44

__genpd_runtime_resume+0x30/0x80

genpd_runtime_resume+0xc8/0x2c0

__rpm_callback+0x48/0x1d8

rpm_callback+0x6c/0x78

rpm_resume+0x490/0x6b4

__pm_runtime_resume+0x50/0x94

irq_chip_pm_get+0x2c/0xa0

__irq_do_set_handler+0x178/0x24c

irq_set_chained_handler_and_data+0x60/0xa4

mxc_gpio_probe+0x160/0x4b0

Cure this by implementing the irq_bus_lock/sync_unlock() interrupt chip

callbacks and handle power management in them as they are invoked from

non-atomic context.

[ tglx: Rewrote change log, added Fixes tag ]