drm/i915: s/PIPEMISC/PIPE_MISC/

This PIPEMISC vs. PIPE_MISC inconsitency is ugly. Unify
the naming (PIPE_MISC is also what bspec has always called it).

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230314130255.23273-3-ville.syrjala@linux.intel.com


Reviewed-by: Jouni Högander <jouni.hogander@intel.com>