drm/panthor: Fix NULL pointer dereference on panthor_fw_unplug

In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Fix NULL pointer dereference on panthor_fw_unplug This patch removes the MCU halt and wait for halt procedures during panthor_fw_unplug() as the MCU can be in a variety of states or the FW may not even be loaded/initialized at all, the latter of which can lead to a NULL pointer dereference. It should be safe on unplug to just disable the MCU without waiting for it to halt as it may not be able to.