ssb: gpio: Use generic_handle_irq_safe()

ssb: gpio: Use generic_handle_irq_safe()

On PREEMPT_RT enabled kernels the demultiplex interrupt handler is force
threaded and runs with interrupts enabled. The invocation of
generic_handle_domain_irq() with interrupts enabled triggers a lockdep
warning due to a non-irq safe lock acquisition.

Instead of disabling interrupts on the driver level, use
generic_handle_domain_irq_safe().

[ tglx: Split out from combo patch ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/YnkfWFzvusFFktSt@linutronix.de