greybus: interface: clean up DME attribute handling

Move all DME defines to the interface code and rename them using common
prefixes (e.g. DME_T and DME_TOSHIBA).

The DDB L1 attributes are defined by MIPI and the Ara attributes are
currently Toshiba specific so move them all out of the Greybus protocol
header.

Also rename the Greybus init-status values using a GB_INIT prefix.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>