mpc512x: Fix problem with I2C access before relocation

This is needed for the upcoming esd MECP5123 board port which uses
I2C EEPROM for environment storage.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
Acked-by: Heiko Schocher<hs@denx.de>

cpu/mpc512x/i2c.c

@@ -33,7 +33,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #include <i2c.h>
 
 /* by default set I2C bus 0 active */
-static unsigned int bus_num = 0;
+static unsigned int bus_num __attribute__ ((section (".data"))) = 0;
 
 #define I2C_TIMEOUT	100
 #define I2C_RETRIES	3