arm64: dts: armada-3720-turris-mox: add 3W power capability to SFP cage

Add maximum-power-milliwatt = 3000 to SFP node of Turris MOX.

Signed-off-by: Marek Behún <kabel@kernel.org>
Fixes: 7109d817 ("arm64: dts: marvell: add DTS for Turris Mox")
Cc: Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>