media: cec: core: Fix kmemleak due to missed rc_free_device() call

The commit dccc0c3ddf ("media: rc: fix race between unregister and
urb/irq callbacks") removed the implicit call to rc_free_device() from
rc_unregister_device(). However, the commit missed to remove the NULL
assignment of adap->rc that is now causing rc_free_device() to never be
called on an allocated rc device.

kmemleak reports following after e.g. dw-hdmi unbind:

unreferenced object 0xffff00010ac10000 (size 4096):
  comm "kworker/u16:1", pid 39, jiffies 4294897739
  hex dump (first 32 bytes):
    20 23 4b 0a 01 00 ff ff 08 00 c1 0a 01 00 ff ff   #K.............
    08 00 c1 0a 01 00 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace (crc e11baccc):
    kmemleak_alloc+0x38/0x44
    __kmalloc_cache_noprof+0x4a8/0x5e0
    rc_allocate_device+0x48/0x2a0
    cec_allocate_adapter+0x3ac/0x800
    dw_hdmi_cec_probe+0x264/0x634
    platform_probe+0xc0/0x188
    really_probe+0x4a4/0x8e0
    __driver_probe_device+0x2f8/0x440
    driver_probe_device+0x60/0x160
    __device_attach_driver+0x1a0/0x2a0
    bus_for_each_drv+0x100/0x1a0
    __device_attach+0x174/0x350
    device_initial_probe+0x90/0xb0
    bus_probe_device+0x4c/0x120
    device_add+0xdec/0x116c
    platform_device_add+0x354/0x598

Remove the assignment of adap->rc to NULL to let cec_delete_adapter()
free the allocated rc device after last user of the cec device exits to
fix the kmemleak.

Fixes: dccc0c3ddf ("media: rc: fix race between unregister and urb/irq callbacks")
Cc: stable@vger.kernel.org
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

drivers/media/cec/core/cec-core.c

@@ -371,9 +371,7 @@ void cec_unregister_adapter(struct cec_adapter *adap)
 		return;
 
 #ifdef CONFIG_MEDIA_CEC_RC
-	/* Note: rc_unregister also calls rc_free */
 	rc_unregister_device(adap->rc);
-	adap->rc = NULL;
 #endif
 	debugfs_remove_recursive(adap->cec_dir);
 #ifdef CONFIG_CEC_NOTIFIER