mmc: zynq_sdhci: Remove global pointer

Driver is not calling gd anywhere that's why there is not need to define
it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/drivers/mmc/zynq_sdhci.c b/drivers/mmc/zynq_sdhci.c
index de404aa..43b9f21 100644
--- a/drivers/mmc/zynq_sdhci.c
+++ b/drivers/mmc/zynq_sdhci.c
@@ -19,8 +19,6 @@
 #include <sdhci.h>
 #include <zynqmp_tap_delay.h>
 
-DECLARE_GLOBAL_DATA_PTR;
-
 struct arasan_sdhci_plat {
 	struct mmc_config cfg;
 	struct mmc mmc;