drm/msm/dsi: Add check for devm_kstrdup()

Add check for the return value of devm_kstrdup() in
dsi_host_parse_dt() to catch potential exception.

Fixes: 958d8d99 ("drm/msm/dsi: parse vsync source from device tree")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/638297/
Link: https://lore.kernel.org/r/20250219040712.2598161-1-haoxiang_li2024@163.com


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