ARM: orion5x: fix d2net gpio initialization

ARM: orion5x: fix d2net gpio initialization

The DT version of this board has a custom file with the gpio
device. However, it does nothing because the d2net_init()
has no caller or prototype:

arch/arm/mach-orion5x/board-d2net.c:101:13: error: no previous prototype for 'd2net_init'

Call it from the board-dt file as intended.

Fixes: 94b0bd366e36 ("ARM: orion5x: convert d2net to Device Tree")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230516153109.514251-10-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>