drm/i915/dpt: drop _common from the DPT file names
With the intel_dpt.[ch] file names vacated, and i915 specific code moved
away, we can rename the intel_dpt_common.[ch] files to the simpler name.
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Link: https://patch.msgid.link/3f2da737a26bb71a7bc05a3e6c456302e3c72656.1772030909.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>