drm/i915 Call get_adjust_train() from clock recovery and channel eq

Move the call to intel_dp_get_adjust_train() out of
intel_dp_update_link_train() and call it instead from the clock recovery
and channel equalization features. A follow up patch will remove the DP
register write from that function, so that it handles only the DPCD
write.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445594525-7174-4-git-send-email-ander.conselvan.de.oliveira@intel.com