drm/i915: Unduplicate chv_data_lane_soft_reset()

The function chv_data_lane_soft_reset() was duplicated in DP and HDMI
code. Move it to intel_dpio_phy.c.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461761065-21195-4-git-send-email-ander.conselvan.de.oliveira@intel.com