drm/i915: s/pipe/transcoder/ when dealing with PIPECONF/TRANSCONF

drm/i915: s/pipe/transcoder/ when dealing with PIPECONF/TRANSCONF

PIPECONF becamse TRANSCONF when HSW introduced the EDP transcoder.
Bigjoiner is making life even more confusing by introducing
a N:1 relationship between pipes and transcoders. In that case
we only enable/configure the transcoder corresponding to the
master pipe. Let's do some renames to make it clear we're dealing
with the transcoder rather than pipe when it comes to
PIPECONF/TRANSCONF.

I decided to leave the _cpu_ part out from the function/macro
names since the PCH transcoder related stuff already has a
_pch_ in their name. So shouldn't be possible to confuse them.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210913144440.23008-6-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>