mvebu: a37xx: Add init for ESPRESSBin Topaz switch

Implement the board-specific network init function for
ESPRESSOBin community board, setting the on-board Topaz
switch port to forward mode and allow network connection
through any of the available Etherenet ports.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Igal Liberman <igall@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Stefan Roese <sr@denx.de>