dt-bindings: dsa: Rewrite Micrel KS8995 in schema

dt-bindings: dsa: Rewrite Micrel KS8995 in schema

After studying the datasheets for some of the KS8995 variants
it becomes pretty obvious that this is a straight-forward
and simple MII DSA switch with one port in (CPU) and four outgoing
ports, and it even supports custom tags by setting a bit in
a special register, and elaborate VLAN handling as all DSA
switches do.

What is a bit odd with KS8995 is that it uses an extra MII-P5
port to access one of the PHYs separately, on the side of the
switch fabric, such as when using a WAN port separately from
a LAN switch in a home router.

Rewrite the terse bindings to YAML, and move to the proper
subdirectory. Include a verbose example to make things clear.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20250625-ks8995-dsa-bindings-v2-1-ce71dce9be0b@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>