media: pulse8-cec: close serio in disconnect, not adap_free

The serio_close() call was moved to pulse8_cec_adap_free(),
but that can be too late if that is called after the serio
core pulled down the serio already, in which case you get
a kernel oops.

Keep it in the disconnect().

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Fixes: 601282d6

 ("media: pulse8-cec: use adap_free callback")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>