drm/i915: Split vlv/chv sprite plane update into noarm+arm pair

drm/i915: Split vlv/chv sprite plane update into noarm+arm pair

Chop vlv_sprite_update() into two halves. Fist half becomes
the _noarm() variant, second part the _arm() variant.

Fortunately I have already previously grouped the register
writes into roughtly the correct order, so the split looks
surprisingly clean.

Looks like most of the hardware logic was copied from the
pre-ctg sprite C, so SPSTRIDE/POS/SIZE are armed by SPSURF,
while the rest are self arming. SPCONSTALPHA is the one
entirely new register that didn't exist in the old sprite C,
and looks like that one is self arming. The CHV pipe B CSC
is also self arming, like the rest of the CHV pipe B
additions.

I didn't have time to capture i915_update_info numbers for
these, but since all the other platforms generally showed
improvements, and crucially no regression, I am fairly
confident this should behave similarly.

Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018115030.3547-10-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>