clk: mediatek: Fix error handling in runtime PM setup

clk: mediatek: Fix error handling in runtime PM setup

devm_pm_runtime_enable() can fail due to memory allocation. The current
code ignores its return value, and when pm_runtime_resume_and_get() fails,
it returns directly without unmapping the shared_io region.

Add error handling for devm_pm_runtime_enable(). Reorder cleanup labels
to properly unmap shared_io on pm_runtime_resume_and_get() failure.

Fixes: 2f7b1d8b5505 ("clk: mediatek: Do a runtime PM get on controllers during probe")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>