Mailbox is restructured as below:

- OMAP1 and OMAP2 parts split out to mach-omap[1-2] respectively.
- struct mbx isolation
- Introduced device model
- Added class interface

Moved omap[1,2] specific parts in mach-omap[1,2]/
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>