net: zynq: Change MDC setup for arm64

MDC setting depends on pclk input clocks which varies across SoC. This
driver is used by xilinx zynq and zynqmp SOC.
Input clock frequence on silicon is 125MHz where divider 64 put
frequency below 2.5MHz requires by spec (125/64=1.95).

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

drivers/net/zynq_gem.c

@@ -57,7 +57,11 @@ DECLARE_GLOBAL_DATA_PTR;
 #define ZYNQ_GEM_NWCFG_SPEED1000	0x000000400 /* 1Gbps operation */
 #define ZYNQ_GEM_NWCFG_FDEN		0x000000002 /* Full Duplex mode */
 #define ZYNQ_GEM_NWCFG_FSREM		0x000020000 /* FCS removal */
+#ifdef CONFIG_ARM64
+#define ZYNQ_GEM_NWCFG_MDCCLKDIV	0x000100000 /* Div pclk by 64, max 160MHz */
+#else
 #define ZYNQ_GEM_NWCFG_MDCCLKDIV	0x0000c0000 /* Div pclk by 48, max 120MHz */
+#endif
 
 #ifdef CONFIG_ARM64
 # define ZYNQ_GEM_DBUS_WIDTH	(1 << 21) /* 64 bit bus */