SPEAr : Support for HW mac id read/write from i2c mem

This patch adds the  support to read and write mac id from i2c
memory.
For reading:
	if (env contains ethaddr)
		pick env ethaddr
	else
		pick ethaddr from i2c memory
For writing:
	chip_config ethaddr XX:XX:XX:XX:XX:XX writes the mac id
	in i2c memory

Signed-off-by: Vipin <vipin.kumar@st.com>

include/asm-arm/arch-spear/spr_defs.h

@@ -35,4 +35,12 @@ struct chip_data {
 	uchar version[32];
 };
 
+/* HW mac id in i2c memory definitions */
+#define MAGIC_OFF	0x0
+#define MAGIC_LEN	0x2
+#define MAGIC_BYTE0	0x55
+#define MAGIC_BYTE1	0xAA
+#define MAC_OFF		0x2
+#define MAC_LEN		0x6
+
 #endif