drm/i915: Rename variables in intel_crtc_compute_config()

Do the s/dev_priv/i915/ and s/pipe_config/crtc_state/ renames
to intel_crtc_compute_config(). I want to start splitting this
up a bit and doing the renames now avoids spreading these old
nameing conventions elsewhere. No functional changes.

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220223131315.18016-5-ville.syrjala@linux.intel.com