drm/panel: Fix a possible null-pointer dereference in jdi_panel_dsi_remove()

In the Linux kernel, the following vulnerability has been resolved: drm/panel: Fix a possible null-pointer dereference in jdi_panel_dsi_remove() In jdi_panel_dsi_remove(), jdi is explicitly checked, indicating that it may be NULL: if (!jdi) mipi_dsi_detach(dsi); However, when jdi is NULL, the function does not return and continues by calling jdi_panel_disable(): err = jdi_panel_disable(&jdi->base); Inside jdi_panel_disable(), jdi is dereferenced unconditionally, which can lead to a NULL-pointer dereference: struct jdi_panel *jdi = to_panel_jdi(panel); backlight_disable(jdi->backlight); To prevent such a potential NULL-pointer dereference, return early from jdi_panel_dsi_remove() when jdi is NULL.