mv_i2c: use structure to replace the direclty define

Add i2c_clk_enable in the cpu specific code, since previous platform it,
while new platform don't need. In the pantheon and armada100 platform,
this function is defined as NULL one.

Acked-by: Heiko Schocher <hs@denx.de>
Acked-by: Prafulla Wadaskar <prafulla@marvell.com>
Signed-off-by: Lei Wen <leiwen@marvell.com>

include/configs/innokom.h

@@ -141,6 +141,7 @@
  * I2C bus
  */
 #define CONFIG_I2C_MV			1
+#define CONFIG_MV_I2C_REG		0x40301680
 #define CONFIG_HARD_I2C			1
 #define CONFIG_SYS_I2C_SPEED			50000
 #define CONFIG_SYS_I2C_SLAVE			0xfe

include/configs/xm250.h

@@ -62,6 +62,7 @@
  * I2C bus
  */
 #define CONFIG_I2C_MV			1
+#define CONFIG_MV_I2C_REG		0x40301680
 #define CONFIG_HARD_I2C			1
 #define CONFIG_SYS_I2C_SPEED			50000
 #define CONFIG_SYS_I2C_SLAVE			0xfe