drm/msm: Fix error return code in msm_drm_init()

When it fail to create crtc_event kthread, it just jump to err_msm_uninit,
while the 'ret' is not updated. So assign the return code before that.

Fixes: 25fdd593 ("drm/msm: Add SDM845 DPU support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Li <liwei391@huawei.com>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Link: https://lore.kernel.org/r/20210705134302.315813-1-liwei391@huawei.com


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>