spi: mt65xx: fix controller deregistration

spi: mt65xx: fix controller deregistration

Make sure to deregister the controller before disabling underlying
resources like clocks during driver unbind.

Fixes: a568231f4632 ("spi: mediatek: Add spi bus for Mediatek MT8173")
Cc: stable@vger.kernel.org	# 4.3: ace145802350
Cc: stable@vger.kernel.org	# 4.3
Cc: Leilk Liu <leilk.liu@mediatek.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20260410081757.503099-2-johan@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>