net: gem: Add OF initialization support

Gem can be directly initialized from DTB.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/netdev.h b/include/netdev.h
index c684014..32b5073 100644
--- a/include/netdev.h
+++ b/include/netdev.h
@@ -91,6 +91,7 @@
 							int txpp, int rxpp);
 int xilinx_ll_temac_eth_init(bd_t *bis, unsigned long base_addr, int flags,
 						unsigned long ctrl_addr);
+int zynq_gem_of_init(const void *blob);
 int zynq_gem_initialize(bd_t *bis, int base_addr, int phy_addr, u32 emio);
 /*
  * As long as the Xilinx xps_ll_temac ethernet driver has not its own interface