spi: sun4i: disable clocks in the remove function

mclk and hclk need to be disabled. Since pm_runtime_disable does
not disable the clocks, use pm_runtime_force_suspend instead.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Takuo Koguchi <takuo.koguchi.sw@hitachi.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>