arm64: dts: marvell: espressobin: Add support for LED2

LED2 is connected to MPP1_2 pin. It is working only on V7 boards.
V5 boards have hw bug which cause that LED2 is non-working.

So enable LED2 only for Espressobin V7 boards.

Note that LED1 is connected to LED_WLAN# pin on miniPCIe card and LED3 to
power supply. Therefore on Espressobin board only LED2 can be controlled
directly from the host. LED1 is possible to control via WiFi card inserted
in miniPCIe slot if driver for particular card supports it.

Signed-off-by: Pali Rohár <pali@kernel.org>
Tested-by: Gérald Kerma <gerald@gk2.net>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>