media: meson/ao-cec: move cec_notifier_cec_adap_register after hw setup

When probed after the HDMI notifier, calling cec_notifier_cec_adap_register()
calls the enable() adapter callback, but the HW is not yet set up.

Moving cec_notifier_cec_adap_register() right before cec_register_adapter()
fixes the following crash:
Ignoring spurious kernel translation fault at virtual address 0000000000000008
[...]
Hardware name: Khadas VIM (DT)
[...]
pc : __do_kernel_fault+0xdc/0x120
lr : __do_kernel_fault+0xdc/0x120
[...]
Call trace:
 __do_kernel_fault+0xdc/0x120
 do_page_fault+0x180/0x458
 do_translation_fault+0x64/0x70
 do_mem_abort+0x3c/0x98
 el1_da+0x20/0x94
 meson_ao_cec_adap_enable+0x30/0x218 [ao_cec]
 __cec_s_phys_addr+0x184/0x270
 cec_s_phys_addr+0x44/0x60
 cec_notifier_cec_adap_register+0x68/0x90
 meson_ao_cec_probe+0xb0/0x288 [ao_cec]
[...]
 el0_svc_compat+0x8/0x10

Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Suggested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 20958f9d ("media: meson/ao-cec: use cec_notifier_cec_adap_(un)register")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>