drm/i915: pass dev_priv explicitly to _MMIO_PPS

drm/i915: pass dev_priv explicitly to _MMIO_PPS

Avoid the implicit dev_priv local variable use, and pass dev_priv
explicitly to the _MMIO_PPS register macro.

While at it, use __to_intel_display() to allow passing in struct
intel_display at a later time.

Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1e9f3ef7eee65946c0e6bf06cc2547a38e8dab78.1716806471.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>