i3c: dw: Add infrastructure for platform-specific implementations

i3c: dw: Add infrastructure for platform-specific implementations

The dw i3c core can be integrated into various SoC devices. Platforms
that use this core may need a little configuration that is specific to
that platform.

Add some infrastructure to allow platform-specific behaviour: common
probe/remove functions, a set of platform hook operations, and a pointer
for platform-specific data in struct dw_i3c_master. Move the common api
into a new (i3c local) header file.

Platforms will provide their own struct platform_driver, which allocates
struct dw_i3c_master, does any platform-specific probe behaviour, and
calls into the common probe.

A future change will add new platform support that uses this
infrastructure.

Signed-off-by: Jeremy Kerr <[email protected]>
Reviewed-by: Joel Stanley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>