drm/bridge/ti-sn65dsi86: Fix implicit declaration to drm_mode_connector_attach_encoder

This function name was changed to drm_connector_attach_encoder().
Unfortunately this driver was posted on the list before that change, and
applied after

Fixes: a095f15c

 ("drm/bridge: add support for sn65dsi86 bridge
driver")
Cc: Sandeep Panda <spanda@codeaurora.org>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Reviewed-by: Sandeep Panda <spanda@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180730174225.257255-1-seanpaul@chromium.org