drm/msm/dp: do not reinitialize phy unless retry during link training

DP PHY re-initialization done using dp_ctrl_reinitialize_mainlink() will
cause PLL unlocked initially and then PLL gets locked at the end of
initialization. PLL_UNLOCKED interrupt will fire during this time if the
interrupt mask is enabled.

However currently DP driver link training implementation incorrectly
re-initializes PHY unconditionally during link training as the PHY was
already configured in dp_ctrl_enable_mainlink_clocks().

Fix this by re-initializing the PHY only if the previous link training
failed.

[drm:dp_aux_isr] *ERROR* Unexpected DP AUX IRQ 0x01000000 when not busy

Fixes: c943b494 ("drm/msm/dp: add displayPort driver support")
Closes: #30


Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com> # sc7280
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/551847/
Link: https://lore.kernel.org/r/1691533190-19335-1-git-send-email-quic_khsieh@quicinc.com


[quic_abhinavk@quicinc.com: added line break in commit text]
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>