net: gem: Remove DECLARE_GLOBAL_DATA_PTR from gem driver

GD is not used anywhere that's why there is no reason to have this macro
in the driver.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/drivers/net/zynq_gem.c b/drivers/net/zynq_gem.c
index 033efb8..a2ed50f 100644
--- a/drivers/net/zynq_gem.c
+++ b/drivers/net/zynq_gem.c
@@ -26,8 +26,6 @@
 #include <asm/arch/sys_proto.h>
 #include <linux/errno.h>
 
-DECLARE_GLOBAL_DATA_PTR;
-
 /* Bit/mask specification */
 #define ZYNQ_GEM_PHYMNTNC_OP_MASK	0x40020000 /* operation mask bits */
 #define ZYNQ_GEM_PHYMNTNC_OP_R_MASK	0x20000000 /* read operation */