drm/msm/dsi: Remove the unneeded result variable

drm/msm/dsi: Remove the unneeded result variable

Return the value msm_dsi_phy_enable() directly instead of storing it in
another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/499621/
Link: https://lore.kernel.org/r/20220826072821.253150-1-ye.xingchen@zte.com.cn
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>