arm64: dts: ti: Add support for AM654 EVM base board

arm64: dts: ti: Add support for AM654 EVM base board

The EValuation Module(EVM) platform for AM654 consists of a
common Base board + one or more of daughter cards, which include:
a) "Personality Modules", which can be specific to a profile, such as
 ICSSG enabled or Multi-media (including audio).
b) SERDES modules, which may be 2 lane PCIe or two port PCIe + USB2
c) Camera daughter card
d) various display panels

Among other options. There are two basic configurations defined which
include an "EVM" configuration and "IDK" (Industrial development kit)
which differ in the specific combination of daughter cards that are
used.

To simplify support, we choose to support just the base board as the
core device tree file and all daughter cards would be expected to be
device tree overlays.

Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>