drm/i915: consolidate interrupt naming scheme

drm/i915: consolidate interrupt naming scheme

The motivation here is we're going to add some new interrupt definitions
and handling outside of the GT interrupts which is all we've managed so
far (with some RPS exceptions). By consolidating the names in the future
we can make thing a bit cleaner as we don't need to define register
names twice, and we can leverage pretty decent overlap in HW registers
since ILK.

To explain briefly what is in the comments: there are two sets of
interrupt masking/enabling registers. At least so far, the definitions
of the two sets overlap. The old code setup distinct names for
interrupts in each set, ie. one for global, and one for ring. This made
things confusing when using the wrong defines in the wrong places.

rebase: Modified VLV bits

v2: Renamed GT_RENDER_MASTER to GT_RENDER_CS_MASTER (Damien)

Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>