drm/msm/dp: reset DP controller before transmit phy test pattern

drm/msm/dp: reset DP controller before transmit phy test pattern

DP controller state can not switch from video ready state to
transmit phy pattern state at run time. DP mainlink has to be
teared down followed by reset controller to default state to have
DP controller switch to transmit phy test pattern state and start
generate specified phy test pattern to sinker once main link setup
again.

Changes in v2:
-- correct Fixes's commit id

Fixes: 52352fe2f866 ("drm/msm/dp: use dp_ctrl_off_link_stream during PHY compliance test run")
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/483563/
Link: https://lore.kernel.org/r/1650995939-28467-2-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>