drm/i915: Parameterize MI_PREDICATE registers

The various MI_PREDICATE registers have per-engine instances.  Today we
only utilize the RCS0 instance of each, but that will likely change in
the future; switch to parameterized register definitions to make these
easier to work with going forward.

Of special note is MI_PREDICATE_RESULT_2; we only use it in one place in
the driver today in HSW-specific code.  It turns out that the bspec
(page 94) lists two different offsets for this register on HSW; one is
in the standard location shared by all other platforms (base + 0x3bc)
and the other is an unusual location (0x2214).  We're using the second,
non-standard offset in i915 today; that offset doesn't exist on any
other platforms (and it's not even 100% clear that it's correct for HSW)
so I've renamed the current non-standard definition to
HSW_MI_PREDICATE_RESULT_2; the new cross-platform parameterized macro
(which is still unused at the moment) uses the standard offset.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220127234334.4016964-5-matthew.d.roper@intel.com