memory: mtk-smi: Add sleep ctrl function

Sleep control means that when the larb goes to sleep, we should wait a bit
until all the current commands are finished. Thus, when the larb runtime
suspends, we need to enable this function to wait until all the existed
commands are finished. When the larb resumes, just disable this function.
This function only improves the safety of bus. Add a new flag for this
function. Prepare for mt8186.

Signed-off-by: Anan Sun <anan.sun@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220113111057.29918-7-yong.wu@mediatek.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>