powerpc: Add T4 LAC device tree binding & defs

The Interlaken is a narrow, high speed channelized chip-to-chip interface. To
facilitate interoperability between a data path device and a look-aside
co-processor, the Interlaken Look-Aside protocol is defined for short
transaction-related transfers. Although based on the Interlaken protocol,
Interlaken Look-Aside is not directly compatible with Interlaken and can be
considered a different operation mode.

The Interlaken LA controller connects internal platform to Interlaken serial
interface. It accepts LA command through software portals, which are system
memory mapped 4KB spaces. The LA commands are then translated into the
Interlaken control words and data words, which are sent on TX side to TCAM
through SerDes lanes.

Signed-off-by: Joe Liccese <joe.liccese@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>