msm: kgsl: Use a consolidated IRQ handler

For some reason while everything else in KGSL was organized into
the kgsl_device hooks  the chip specific interrupt handler pointer
was being passed through the device registration function. Make
the IRQ handler work the same way as the other hooks.  this reduces
the complexity and reduces the chip specific variables passed into
the generic registration to just one pointer.

Change-Id: Ic0dedbadff1641cbca80593e91744dbb6dcfd2cc
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>