Revert "ARM: EXYNOS: Select SPARSE_IRQ for Exynos". Mali isn't yet ready

This reverts commit 6e726ea4f50e7fea5844a2a0fee29d6d3d2e8bdf.
Revert "ARM: EXYNOS: Remove mach/irqs.h header". For non-sparse IRQs

This reverts commit 1f893d60d213ca7fd035b20d9072c9e1781ee99f.
return back def required for non-sparse IRQs