drm/i915: add ironlake_irq_reset
drm/i915: add ironlake_irq_reset

To merge the common code of ironlake_irq_preinstall and
ironlake_irq_uninstall.

We should also probably do something about that HSWSTAM write on a
later commit.

Signed-off-by: Paulo Zanoni <cc0e04a2103c45cd195651d976f79813d0f66bdf@intel.com>
[danvet: Fix compile fail due to drm_i915_private_t typedef removal.]
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs