drm/msm/dpu: fix error check return value of irq_of_parse_and_map()

The irq_of_parse_and_map() function returns 0 on failure, and does not
return a negative value anyhow, so never enter this conditional branch.

Fixes: 25fdd593 ("drm/msm: Add SDM845 DPU support")
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/483291/
Link: https://lore.kernel.org/r/20220425090947.3498897-1-lv.ruyi@zte.com.cn


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>