This patch adds a generic mailbox interface considering IVA
(Image Video Accelerator) use on 2420, but this patch itself
doesn't contain any IVA driver.
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>