spmi: pmic-arb: use irq_chip callback to set spmi irq wakeup capability

Currently the driver sets the pmic arbiter core interrupt as wakeup capable
irrespective of the child irqs which causes the system to wakeup
unnecessarily. To fix this, set the core interrupt as wakeup capable
only if any of the child irqs request for it. Do this by marking it as
wakeup capable in the irq_set_wake callback.

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>