media: dvb-frontends: m88ds3103: Fix a memory leak in an error handling path of m88ds3103_probe()

If an error occurs after a successful i2c_mux_add_adapter(), then
i2c_mux_del_adapters() should be called to free some resources, as
already done in the remove function.

Fixes: e6089fec ("media: m88ds3103: Add support for ds3103b demod")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>