boards: adi: Add AD-APARD32690-SL

Add board support for the ADI AD-APARD32690-SL. The platform is based on
a MAX32690 microcontroller, it has an Arduino-Mega compatible header and
2 PMOD connectors. Also, a 10 Mbps single-pair Ethernet link is enabled
by using the ADIN1110 10BASE-T1L MAC/PHY.

Signed-off-by: Ciprian Regus <ciprian.regus@analog.com>