arm64: dts: marvell: espressobin: Get rid of duplicate serial aliases

The included armada-37xx.dtsi already defines these two aliases.

Signed-off-by: Andre Heider <a.heider@gmail.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>