drm/i915/dp: move link_bw and rate_select debugging where used

We call intel_dp_compute_rate() in intel_dp_compute_config() only to be
able to debug log the link_bw and rate_select parameters; we don't use
the parameters here for anything else. We call intel_dp_compute_rate()
again during link training where we actually need and use the
parameters.

Move the debug logging of link_bw and rate_select to
intel_dp_link_training_clock_recovery(), and clean up the extra
intel_dp_compute_rate() call and extra clutter from the already
overcrowded intel_dp_compute_config().

v2: Rewrote commit message (Rodrigo, Manasi)

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c5cf6a179e2d244eceb6bb80a792765d9efbee4f.1524730974.git.jani.nikula@intel.com