macb: support higher rate GEM MDIO clock divisors

GEM devices support larger clock divisors and have a different
range of divisors.  Program the MDIO clock divisors based on the
device type.

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Tested-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index d50057c..354ed8f 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -135,6 +135,9 @@
 #define MACB_IRXFCS_OFFSET			19
 #define MACB_IRXFCS_SIZE			1
 
+/* GEM specific NCFGR bitfields. */
+#define GEM_CLK_OFFSET				18
+#define GEM_CLK_SIZE				3
 /* Bitfields in NSR */
 #define MACB_NSR_LINK_OFFSET			0
 #define MACB_NSR_LINK_SIZE			1
@@ -249,6 +252,14 @@
 #define MACB_CLK_DIV32				2
 #define MACB_CLK_DIV64				3
 
+/* GEM specific constants for CLK. */
+#define GEM_CLK_DIV8				0
+#define GEM_CLK_DIV16				1
+#define GEM_CLK_DIV32				2
+#define GEM_CLK_DIV48				3
+#define GEM_CLK_DIV64				4
+#define GEM_CLK_DIV96				5
+
 /* Constants for MAN register */
 #define MACB_MAN_SOF				1
 #define MACB_MAN_WRITE				1