arm64: dts: uDPU: SFP cages support 3W modules

The SFP cages are designed to support up to 3W modules, such as G.hn,
G.fast and MoCA modules. Although there is no way for such modules to
declare to software that they consume 3W, we document in DT that this
is the designed power level for these cages.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>