spmi: pmic-arb: fix missing interrupts

irq_enable is called when the device resumes. Note that the
irq_enable is called regardless of whether the interrupt was
marked enabled/disabled in the descriptor or whether it was
masked/unmasked at the controller while resuming.

The current driver unconditionally clears the interrupt in its
irq_enable callback. This is dangerous as any interrupts that
happen right before the resume could be missed.
Remove the irq_enable callback and use mask/unmask instead.

Also remove struct pmic_arb_irq_spec as it serves no real purpose.
It is used only in the translate function and the code is much
cleaner without it.

Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>