Add drv private opaque structure to have bus level
structure for multibus support.
Signed-off-by: NGovind Singh <govinds@codeaurora.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200506094400.4740-3-govinds@codeaurora.org