ARM: s5pv310: update IRQ combiner to use chained entry/exit functions

This patch updates the IRQ combiner chained IRQ handler code to use the
chained IRQ enter/exit functions in order to function correctly on
primary controllers with different methods of flow control.

This is required for the GIC to move to fasteoi interrupt handling.

Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>